ORCID Profile
0000-0003-0980-1499
Current Organisation
INAF-Osservatorio Astronomico di Padova
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Astronomical and Space Sciences | Cosmology and Extragalactic Astronomy
Publisher: American Astronomical Society
Date: 07-2023
Abstract: The abundance of carbon relative to oxygen (C/O) is a promising probe of star formation history in the early universe, as the ratio changes with time due to production of these elements by different nucleosynthesis pathways. We present a measurement of log ( C / O ) = − 1.01 ± 0.12 (stat) ±0.15 (sys) in a z = 6.23 galaxy observed as part of the GLASS–JWST Early Release Science Program. Notably, we achieve good precision thanks to the detection of the rest-frame ultraviolet O iii ], C iii ], and C iv emission lines delivered by JWST/NIRSpec. The C/O abundance is ∼0.8 dex lower than the solar value and is consistent with the expected yield from core-collapse supernovae, indicating that longer-lived intermediate-mass stars have not fully contributed to carbon enrichment. This in turn implies rapid buildup of a young stellar population with age ≲100 Myr in a galaxy seen ∼900 Myr after the big bang. Our chemical abundance analysis is consistent with spectral energy distribution modeling of JWST/NIRCam photometric data, which indicates a current stellar mass log M * / M ☉ = 8.4 − 0.2 + 0.4 and specific star formation rate ≃20 Gyr −1 . These results showcase the value of chemical abundances and C/O in particular to study the earliest stages of galaxy assembly.
Publisher: Oxford University Press (OUP)
Date: 17-02-2019
DOI: 10.1093/MNRAS/STZ460
Publisher: American Astronomical Society
Date: 08-2022
Abstract: The GLASS-JWST Early Release Science (hereafter GLASS-JWST-ERS) Program will obtain and make publicly available the deepest extragalactic data of the ERS c aign. It is primarily designed to address two key science questions, namely, “what sources ionized the universe and when?” and “how do baryons cycle through galaxies?”, while also enabling a broad variety of first look scientific investigations. In primary mode, it will obtain NIRISS and NIRSpec spectroscopy of galaxies lensed by the foreground Hubble Frontier Field cluster, Abell 2744. In parallel, it will use NIRCam to observe two fields that are offset from the cluster center, where lensing magnification is negligible, and which can thus be effectively considered blank fields. In order to prepare the community for access to this unprecedented data, we describe the scientific rationale, the survey design (including target selection and observational setups), and present pre-commissioning estimates of the expected sensitivity. In addition, we describe the planned public releases of high-level data products, for use by the wider astronomical community.
Publisher: American Astronomical Society
Date: 04-2023
Abstract: We present the spectroscopic confirmation of a protocluster at z = 7.88 behind the galaxy cluster Abell 2744 (hereafter A2744-z7p9OD). Using JWST NIRSpec, we find seven galaxies within a projected radius of 60 kpc. Although the galaxies reside in an overdensity around ≳20× greater than a random volume, they do not show strong Ly α emission. We place 2 σ upper limits on the rest-frame equivalent width –28 Å. Based on the tight upper limits to the Ly α emission, we constrain the volume-averaged neutral fraction of hydrogen in the intergalactic medium to be x HI 0.45 (68% C i ). Using an empirical M UV – M halo relation for in idual galaxies, we estimate that the total halo mass of the system is ≳4 × 10 11 M ⊙ . Likewise, the line-of-sight velocity dispersion is estimated to be 1100 ± 200 km s −1 . Using an empirical relation, we estimate the present-day halo mass of A2744-z7p9OD to be ∼2 × 10 15 M ⊙ , comparable to the Coma cluster. A2744-z7p9OD is the highest redshift spectroscopically confirmed protocluster to date, demonstrating the power of JWST to investigate the connection between dark-matter halo assembly and galaxy formation at very early times with medium-deep observations at hr total exposure time. Follow-up spectroscopy of the remaining photometric candidates of the overdensity will further refine the features of this system and help characterize the role of such overdensities in cosmic reionization.
Publisher: American Astronomical Society
Date: 05-02-2018
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201732507
Abstract: Context. Superclusters form from the largest enhancements in the primordial density perturbation field and extend for tens of Mpc, tracing the large-scale structure of the Universe. X-ray detections and systematic characterisations of superclusters and the properties of their galaxies have only been possible in the last few years. Aims. We characterise XLSSsC N01, a rich supercluster at z ~ 0.3 detected in the XXL Survey, composed of X-ray clusters of different virial masses and X-ray luminosities. As one of the first studies on this topic, we investigate the stellar populations of galaxies in different environments in the supercluster region. Methods. We study a magnitude-limited ( r ≤ 20) and a mass-limited s le (log( M * ∕ M ⊙ ) ≥ 10.8) of galaxies in the virialised region and in the outskirts of 11 XLSSsC N01 clusters, in high-density field regions, and in the low-density field. We compute the stellar population properties of galaxies using spectral energy distribution (SED) and spectral fitting techniques, and study the dependence of star formation rates (SFR), colours, and stellar ages on environment. Results. For r ≤ 20, the fraction of star-forming/blue galaxies, computed either from the specific-SFR (sSFR) or rest-frame colour, shows depletion within the cluster virial radii, where the number of galaxies with log (sSFR/ yr −1 ) −12 and with ( g − r ) restframe 0.6 is lower than in the field. For log( M * ∕ M ⊙ ) ≥ 10.8, no trends with environment emerge, as massive galaxies are mostly already passive in all environments. No differences among low- and high-density field members and cluster members emerge in the sSFR-mass relation in the mass-complete regime. Finally, the luminosity-weighted age–mass relation of the passive populations within cluster virial radii show signatures of recent environmental quenching. Conclusions. The study of luminous and massive galaxies in this supercluster shows that while environment has a prominent role in determining the fractions of star-forming/blue galaxies, its effects on the star formation activity in star-forming galaxies are negligible.
Publisher: American Astronomical Society
Date: 04-2021
Abstract: We present constraints on the physical properties (including stellar mass, age, and star formation rate) of 207 6 ≲ z ≲ 8 galaxy candidates from the Reionization Lensing Cluster Survey (RELICS) and Spitzer-RELICS surveys. We measure photometry using T-PHOT and perform spectral energy distribution fitting using EA z Y and BAGPIPES. Of the 207 candidates for which we could successfully measure (or place limits on) Spitzer fluxes, 23 were demoted to likely z 4. Among the high- z candidates, we find intrinsic stellar masses between 1 × 10 6 M ⊙ and 4 × 10 9 M ⊙ , and rest-frame UV absolute magnitudes between −22.6 and −14.5 mag. While our s le is mostly comprised of L m UV / L m UV * 1 galaxies, it extends to L m UV / L m UV * ∼ 2 . Our s le spans ∼4 orders of magnitude in stellar mass and star formation rates, and exhibits ages that range from maximally young to maximally old. We highlight 11 z ≥ 6.5 galaxies with detections in Spitzer/IRAC imaging, several of which show evidence for some combination of evolved stellar populations, large contributions of nebular emission lines, and/or dust. Among these is PLCKG287+32-2013, one of the brightest z ∼ 7 candidates known (AB mag 24.9 at 1.6 μ m) with a Spitzer 3.6 μ m flux excess suggesting strong [O iii ] + H- β emission (∼1000 Å rest-frame equivalent width). We discuss the possible uses and limits of our s le and present a public catalog of Hubble + Spitzer photometry along with physical property estimates for all objects in the s le. Because of their apparent brightnesses, high redshifts, and variety of stellar populations, these objects are excellent targets for follow-up with the James Webb Space Telescope.
Publisher: American Astronomical Society
Date: 20-01-2020
Publisher: American Astronomical Society
Date: 04-2023
Abstract: We present a first look at the reddest 2–5 μ m sources found in deep images from the GLASS Early Release Science program. We undertake a general search, i.e., not looking for any particular spectral signatures, for sources detected only in bands redder than is reachable with the Hubble Space Telescope, and which would likely not have been identified in pre-JWST surveys. We search for sources down to AB ∼27 (corresponding to σ detection threshold) in any of the F200W to F444W filters, with a magnitude excess relative to F090W to F150W bands. Fainter than F444W we find 56 such sources of which 37 have reasonably constrained spectral energy distributions to which we can fit photometric redshifts. We find the majority of this population (∼65%) as 2 z 6 star-forming low-attenuation galaxies that are faint at rest-frame ultraviolet-optical wavelengths, have stellar masses 10 8.5 –10 9.5 M ⊙ , and have observed fluxes at μ m boosted by a combination of the Balmer break and emission lines. The typical implied rest equivalent widths are ∼200 Å with some extreme objects up to ∼1000 Å. This is in contrast with brighter magnitudes where the red sources tend to be z 3 quiescent galaxies and dusty star-forming objects. Our general selection criteria for red sources allow us to independently identify other phenomena as erse as extremely low-mass (∼10 8 M ⊙ ) quiescent galaxies at z 1, recovering recently identified z 11 galaxies and a very cool brown dwarf.
Publisher: American Astronomical Society
Date: 20-12-2016
Publisher: American Astronomical Society
Date: 10-04-2017
Publisher: Oxford University Press (OUP)
Date: 21-11-2018
Publisher: Oxford University Press (OUP)
Date: 23-04-2015
DOI: 10.1093/MNRAS/STV670
Publisher: Oxford University Press (OUP)
Date: 19-05-2016
Publisher: American Astronomical Society
Date: 24-05-2013
Publisher: American Astronomical Society
Date: 04-06-2018
Publisher: American Astronomical Society
Date: 24-05-2013
Publisher: Oxford University Press (OUP)
Date: 08-12-2022
Abstract: Spiral galaxies undergo strong ram-pressure effects when they fall into the galaxy cluster potential. As a consequence, their gas is stripped to form extended tails within which star formation can happen, giving them the typical jellyfish appearance. The ultraviolet imaging observations of jellyfish galaxies provide an opportunity to understand ongoing star formation in the stripped tails. We report the ultraviolet observations of the jellyfish galaxies JW39, JO60, JO194 and compare with observations in optical continuum and Hα. We detect knots of star formation in the disc and tails of the galaxies and find that their UV and Hα flux are well correlated. The optical emission line ratio maps of these galaxies are used to identify for every region the emission mechanism, due to either star formation, LINER or a mix of the two phenomena. The star-forming regions in the emission line maps match very well with the regions having significant UV flux. The central regions of two galaxies (JW39, JO194) show a reduction in UV flux which coincides with composite or LINER regions in the emission line maps. The galaxies studied here demonstrate significant star formation in the stripped tails, suppressed star formation in the central regions and present a possible case of accelerated quenching happening in jellyfish galaxies.
Publisher: American Astronomical Society
Date: 10-11-2016
Publisher: American Astronomical Society
Date: 24-05-2013
Publisher: American Astronomical Society
Date: 04-2023
Abstract: We use the GLASS-JWST Early Release Science NIRCam parallel observations to provide a first view of the UV continuum properties of NIRCam/F444W selected galaxies at 4 z 7. By combining multiwavelength NIRCam observations, we constrain the UV continuum slope for a s le of 401 galaxies with stringent quality controls. We find that % of the galaxies are blue star-forming galaxies with very low levels of dust ( Av β ∼ 0.01 ± 0.33). We find no statistically significant correlation for UV slope with redshift or UV magnitude. However, we find that in general galaxies at higher redshifts and fainter UV magnitudes have steeper UV slopes. We find a statistically significant correlation for UV slope with stellar mass, with galaxies with higher stellar mass showing shallower UV slopes. In idual fits to some of our galaxies reach the bluest UV slopes of β ∼ −3.1 allowed by stellar population models used in this analysis. Therefore, it is likely that stellar population models with a higher amount of Lyman continuum leakage, active galactic nucleus effects, and/or Population III contributions are required to accurately reproduce the rest-UV and optical properties of some of our bluest galaxies. This dust-free early view confirms that our current cosmological understanding of gradual mass + dust buildup of galaxies with cosmic time is largely accurate to describe the ∼0.7–1.5 Gyr age window of the universe. The abundance of a large population of UV faint dust-poor systems may point to a dominance of low-mass galaxies at z 6 playing a vital role in cosmic reionization.
Publisher: American Astronomical Society
Date: 24-05-2013
Publisher: Oxford University Press (OUP)
Date: 08-2022
Abstract: We model satellite quenching at z ∼ 1 by combining 14 massive (1013.8 & Mhalo/M⊙ & 1015) clusters at 0.8 & z & 1.3 from the GOGREEN and GCLASS surveys with accretion histories of 56 redshift-matched analogues from the IllustrisTNG simulation. Our fiducial model, which is parametrized by the satellite quenching time-scale (τquench), accounts for quenching in our simulated satellite population both at the time of infall by using the observed coeval field quenched fraction and after infall by tuning τquench to reproduce the observed satellite quenched fraction versus stellar mass trend. This model successfully reproduces the observed satellite quenched fraction as a function of stellar mass (by construction), projected cluster-centric radius, and redshift and is consistent with the observed field and cluster stellar mass functions at z ∼ 1. We find that the satellite quenching time-scale is mass dependent, in conflict with some previous studies at low and intermediate redshift. Over the stellar mass range probed (M⋆ & 1010 M⊙), we find that the satellite quenching time-scale decreases with increasing satellite stellar mass from ∼1.6 Gyr at 1010 M⊙ to ∼0.6−1 Gyr at 1011 M⊙ and is roughly consistent with the total cold gas (HI + H2) depletion time-scales at intermediate z, suggesting that starvation may be the dominant driver of environmental quenching at z & 2. Finally, while environmental mechanisms are relatively efficient at quenching massive satellites, we find that the majority ($\\sim 65{\\!-\\!}80{{\\ \\rm per\\ cent}}$) of ultra-massive satellites (M⋆ & 1011 M⊙) are quenched prior to infall.
Publisher: American Astronomical Society
Date: 03-2022
Abstract: Ram pressure stripping (RPS) by the intracluster medium is one of the most advocated mechanisms that affect the properties of cluster galaxies. A recent study based on a small s le has found that many galaxies showing strong signatures of RPS also possess an active galactic nucleus (AGN), suggesting a possible correlation between the two phenomena. This result has not been confirmed by a subsequent study. Building upon previous findings, here we combine MUSE observations conducted within the GASP program and a general survey of the literature to robustly measure the AGN fraction in ram-pressure-stripped cluster galaxies using Baldwin–Phillips–Terlevich emission line diagrams. Considering a s le of 115 ram-pressure-stripped galaxies with stellar masses ≥ 10 9 M ⊙ , we find an AGN fraction of ∼27%. This fraction strongly depends on stellar mass: it raises to 51% when only ram-pressure-stripped galaxies of masses M * ≥ 10 10 M ⊙ are considered. We then investigate whether the AGN incidence is in excess in ram-pressure-stripped galaxies compared to nonstripped galaxies using as a comparison a s le of noncluster galaxies observed by the MaNGA survey. Considering mass-matched s les, we find that the incidence of AGN activity is significantly higher (at a confidence level .95%) when RPS is in the act, supporting the hypothesis of an AGN–ram pressure connection.
Publisher: American Astronomical Society
Date: 28-11-2017
Publisher: American Astronomical Society
Date: 29-08-2017
Publisher: Oxford University Press (OUP)
Date: 23-04-2020
Abstract: We present JVLA-C observations of the H i gas in JO204, one of the most striking jellyfish galaxies from the GASP survey. JO204 is a massive galaxy in the low-mass cluster A957 at z = 0.04243. The H i map reveals an extended 90 kpc long ram-pressure stripped tail of neutral gas, stretching beyond the 30 kpc long ionized gas tail and pointing away from the cluster centre. The H i mass seen in emission is $(1.32\\pm 0.13) \\times 10^{9} \\, \\rm M_{\\odot }$, mostly located in the tail. The northern part of the galaxy disc has retained some H i gas, while the southern part has already been completely stripped and displaced into an extended unilateral tail. Comparing the distribution and kinematics of the neutral and ionized gas in the tail indicates a highly turbulent medium. Moreover, we observe associated H i absorption against the 11 mJy central radio continuum source with an estimated H i absorption column density of 3.2 × 1020 cm−2. The absorption profile is significantly asymmetric with a wing towards higher velocities. We modelled the H i absorption by assuming that the H i and ionized gas discs have the same kinematics in front of the central continuum source, and deduced a wider absorption profile than observed. The observed asymmetric absorption profile can therefore be explained by a clumpy, rotating H i gas disc seen partially in front of the central continuum source, or by ram pressure pushing the neutral gas towards the centre of the continuum source, triggering the AGN activity.
Publisher: American Astronomical Society
Date: 09-2022
Abstract: We present a study of the orbits, environments, and morphologies of 13 ram-pressure stripped galaxies in the massive, intermediate redshift ( z ∼ 0.3−0.4) galaxy clusters A2744 and A370, using MUSE integral-field spectroscopy and Hubble Space Telescope imaging from the Frontier Fields Program. We compare different measures of the locations and morphologies of the stripped s le with a s le of six post-starburst galaxies identified within the same clusters, as well as the general cluster population. We calculate the phase-space locations of all cluster galaxies and carry out a substructure analysis, finding that the ram-pressure stripped galaxies in A370 are not associated with any substructures, but are likely isolated infalling galaxies. In contrast, the ram-pressure stripped galaxies in A2744 are strictly located within a high-velocity substructure, moving through a region of dense X-ray emitting gas. We conclude that their ram-pressure interactions are likely to be the direct result of the merger between two components of the cluster. Finally, we study the morphologies of the stripped and post-starburst galaxies, using numerical measures to quantify the level of visual disturbances. We explore any morphological deviations of these galaxies from the cluster population, particularly the weaker cases that have been confirmed via the presence of ionized gas tails to be undergoing ram-pressure stripping, but are not strongly visually disturbed in the broadband data. We find that the stripped s le galaxies are generally ergent from the general cluster s le, with post-starburst galaxies being intermediary in morphology between stripped galaxies and red passive cluster members.
Publisher: Oxford University Press (OUP)
Date: 02-06-2018
Publisher: Springer Science and Business Media LLC
Date: 18-02-2021
DOI: 10.1038/S41467-021-21207-2
Abstract: Adjuvant systemic therapies are now routinely used following resection of stage III melanoma, however accurate prognostic information is needed to better stratify patients. We use differential expression analyses of primary tumours from 204 RNA-sequenced melanomas within a large adjuvant trial, identifying a 121 metastasis-associated gene signature. This signature strongly associated with progression-free (HR = 1.63, p = 5.24 × 10 −5 ) and overall survival (HR = 1.61, p = 1.67 × 10 −4 ), was validated in 175 regional lymph nodes metastasis as well as two externally ascertained datasets. The machine learning classification models trained using the signature genes performed significantly better in predicting metastases than models trained with clinical covariates ( p AUROC = 7.03 × 10 −4 ), or published prognostic signatures ( p AUROC 0.05). The signature score negatively correlated with measures of immune cell infiltration (ρ = −0.75, p 2.2 × 10 −16 ), with a higher score representing reduced lymphocyte infiltration and a higher 5-year risk of death in stage II melanoma. Our expression signature identifies melanoma patients at higher risk of metastases and warrants further evaluation in adjuvant clinical trials.
Publisher: American Astronomical Society
Date: 17-03-2017
Publisher: American Astronomical Society
Date: 12-2021
Abstract: Making use of both MUSE observations of 85 galaxies from the survey GASP (GAs Stripping Phenomena in galaxies with MUSE) and a large s le from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory survey), we investigate the distribution of gas metallicity gradients as a function of stellar mass for local cluster and field galaxies. Overall, metallicity profiles steepen with increasing stellar mass up to 10 10.3 M ⊙ and flatten out at higher masses. Combining the results from the metallicity profiles and the stellar mass surface density gradients, we propose that the observed steepening is a consequence of local metal enrichment due to in situ star formation during the inside-out formation of disk galaxies. The metallicity gradient−stellar mass relation is characterized by a rather large scatter, especially for 10 9.8 M ⋆ / M ⊙ 10 10.5 , and we demonstrate that metallicity gradients anti-correlate with the galaxy gas fraction. Focusing on the galaxy environment, at any given stellar mass, cluster galaxies have systematically flatter metallicity profiles than their field counterparts. Many subpopulations coexist in clusters: galaxies with shallower metallicity profiles appear to have fallen into their present host halo sooner and have experienced the environmental effects for a longer time than cluster galaxies with steeper metallicity profiles. Recent galaxy infallers, like galaxies currently undergoing ram pressure stripping, show metallicity gradients more similar to those of field galaxies, suggesting they have not felt the effect of the cluster yet.
Publisher: Oxford University Press (OUP)
Date: 13-10-2021
Abstract: We present deep Jansky Very Large Array observations at 1.4 and 2.7 GHz (full polarization), as well as optical OmegaWINGS/WINGS and X-ray observations of two extended radio galaxies in the IIZW108 galaxy cluster at z = 0.04889. They show a bent tail morphology in agreement with a radio lobed galaxy falling into the cluster potential. Both galaxies are found to possess properties comparable with narrow-angle tail galaxies in the literature even though they are part of a low mass cluster. We find a spectral index steepening and an increase in fractional polarization through the galaxy jets and an ordered magnetic field component mostly aligned with the jet direction. This is likely caused by either shear due to the velocity difference of the intracluster medium and the jet fluid and/or magnetic draping of the intracluster medium across the galaxy jets. We find clear evidence that one source is showing two active galactic nuclei (AGN) outbursts from which we expect the AGN has never turned off completely. We show that pure standard electron cooling cannot explain the jet length. We demonstrate therefore that these galaxies can be used as a laboratory to study gentle re-acceleration of relativistic electrons in galaxy jets via transition from laminar to turbulent motion.
Publisher: American Astronomical Society
Date: 10-2022
Abstract: We report the first gas-phase metallicity map of a distant galaxy measured with the James Webb Space Telescope (JWST). We use the NIRISS slitless spectroscopy acquired by the GLASS Early Release Science program to spatially resolve the rest-frame optical nebular emission lines in a gravitationally lensed galaxy at z = 3.06 behind the A2744 galaxy cluster. This galaxy (dubbed GLASS-Zgrad1) has stellar mass ∼10 8.6 M ⊙ , instantaneous star formation rate ∼8.6 M ⊙ yr −1 (both corrected for lensing magnification), and global metallicity one-fourth solar. From its emission-line maps ([O iii ], H β , H γ , [Ne iii ], and [O ii ]), we derive its spatial distribution of gas-phase metallicity using a well-established forward-modeling Bayesian inference method. The exquisite resolution and sensitivity of JWST/NIRISS, combined with lensing magnification, enable us to resolve this z ∼ 3 dwarf galaxy in ≳50 resolution elements with sufficient signal, an analysis hitherto not possible. We find that the radial metallicity gradient of GLASS-Zgrad1 is strongly inverted (i.e., positive): Δ log ( O / H ) / Δ r = 0.165 ± 0.023 dex kpc −1 . This measurement is robust at ≳ 4 − σ confidence level against known systematics. This positive gradient may be due to tidal torques induced by a massive nearby (∼15 kpc projected) galaxy, which can cause inflows of metal-poor gas into the central regions of GLASS-Zgrad1. These first results showcase the power of JWST wide-field slitless spectroscopic modes to resolve the mass assembly and chemical enrichment of low-mass galaxies in and beyond the peak epoch of cosmic star formation ( z ≳ 2). Reaching masses ≲ 10 9 M ⊙ at these redshifts is especially valuable to constrain the effects of galactic feedback and environment and is possible only with JWST’s new capabilities.
Publisher: American Astronomical Society
Date: 2023
Abstract: We present the first James Webb Space Telescope/NIRCam-led determination of 7 z 9 galaxy properties based on broadband imaging from 0.8 to 5 μ m as part of the GLASS-JWST Early Release Science program. This is the deepest data set acquired at these wavelengths to date, with an angular resolution ≲0.″14. We robustly identify 13 galaxies with signal-to-noise ratio ≳ 8 in F444W from 8 arcmin 2 of data at m AB ≤ 28 from a combination of dropout and photometric redshift selection. From simulated data modeling, we estimate the dropout s le purity to be ≳90%. We find that the number density of these F444W-selected sources is broadly consistent with expectations from the UV luminosity function determined from Hubble Space Telescope data. We characterize galaxy physical properties using a Bayesian spectral energy distribution fitting method, finding a median stellar mass of 10 8.5 M ⊙ and age 140 Myr, indicating they started ionizing their surroundings at redshift z 9.5. Their star formation main sequence is consistent with predictions from simulations. Lastly, we introduce an analytical framework to constrain main-sequence evolution at z 7 based on galaxy ages and basic assumptions, through which we find results consistent with expectations from cosmological simulations. While this work only gives a glimpse of the properties of typical galaxies that are thought to drive the reionization of the universe, it clearly shows the potential of JWST to unveil unprecedented details of galaxy formation in the first billion years.
Publisher: EDP Sciences
Date: 03-2023
DOI: 10.1051/0004-6361/202245070
Abstract: Context. Observational studies have widely demonstrated that galaxy physical properties are strongly affected by the surrounding environment. On one side, gas inflows provide galaxies with new fuel for star formation. On the other side, the high temperatures and densities of the medium are expected to induce quenching in the star formation. Observations of large structures, in particular filaments at the cluster outskirts ( r 2 r 200 ), are currently limited to the low redshift Universe. Deep and wide photometric data, better if combined with spectroscopic redshifts, are required to explore several scenarios on galaxy evolution at intermediate redshift. Aims. We present a multi-band dataset for the cluster MACS J0416.1-2403 ( z = 0.397), observed in the context of the Galaxy Assembly as a function of Mass and Environment with the VLT Survey Telescope (VST-GAME) survey. The project is aimed at gathering deep ( r 24.4) and wide (approx. 20x20 Mpc 2 ) observations at optical ( u , ɡ , r , i , VST) wavelengths for six massive galaxy clusters at 0.2 z 0.6, complemented with near-infrared data ( Y , J , Ks , VISTA, ESO public survey GCAV). The aim is to investigate galaxy evolution in a wide range of stellar masses and environmental conditions. This work describes the photometric analysis of the cluster and the definition of a density field, which will be a key ingredient for further studies on galaxy properties in the cluster outskirts. Methods. We extracted sources paying particular attention to recovering the faintest ones and simultaneously flagging point sources and sources with photometry affected by artifacts in the images. We combined all the extractions in a multiband catalog that is used to derive photometric redshifts through spectral energy distribution (SED) fitting. We then defined cluster memberships up to 5 r 200 from the cluster core and measure the density field, comparing galaxy properties in different environments. Results. We find that the ɡ – r colors show bimodal behaviors in all the environments, but the peak of the distribution of red galaxies shifts toward redder colors with increasing density, and the fraction of galaxies in the blue cloud increases with decreasing density. We also found three overdense regions in the cluster outskirts at r ~ 5 r 200 . Galaxies in these structures have mean densities and luminosities similar to those of the cluster core. The color of galaxies suggests the presence of evolved galaxy populations, an insight into preprocessing phenomena over these substructures. We release the multiband catalog, down to the completeness limit of r 24.4 mag.
Publisher: American Astronomical Society
Date: 23-03-2022
Abstract: Virgo is the nearest galaxy cluster it is thus ideal for studies of galaxy evolution in dense environments in the local universe. It is embedded in a complex filamentary network of galaxies and groups, which represents the skeleton of the large-scale Laniakea supercluster. Here we assemble a comprehensive catalog of galaxies extending up to ∼12 virial radii in projection from Virgo to revisit the cosmic-web structure around it. This work is the foundation of a series of papers that will investigate the multiwavelength properties of galaxies in the cosmic web around Virgo. We match spectroscopically confirmed sources from several databases and surveys including HyperLeda, NASA Sloan Atlas, NASA/IPAC Extragalactic Database, and ALFALFA. The s le consists of ∼7000 galaxies. By exploiting a tomographic approach, we identify 13 filaments, spanning several megaparsecs in length. Long h –1 Mpc filaments, tend to be thin ( h –1 Mpc in radius) and with a low-density contrast ( ), while shorter filaments show a larger scatter in their structural properties. Overall, we find that filaments are a transitioning environment between the field and cluster in terms of local densities, galaxy morphologies, and fraction of barred galaxies. Denser filaments have a higher fraction of early-type galaxies, suggesting that the morphology–density relation is already in place in the filaments, before galaxies fall into the cluster itself. We release the full catalog of galaxies around Virgo and their associated properties.
Publisher: Springer Science and Business Media LLC
Date: 25-05-2016
DOI: 10.1038/NATURE18006
Abstract: Quiescent galaxies with little or no ongoing star formation dominate the population of galaxies with masses above 2 × 10(10) times that of the Sun the number of quiescent galaxies has increased by a factor of about 25 over the past ten billion years (refs 1-4). Once star formation has been shut down, perhaps during the quasar phase of rapid accretion onto a supermassive black hole, an unknown mechanism must remove or heat the gas that is subsequently accreted from either stellar mass loss or mergers and that would otherwise cool to form stars. Energy output from a black hole accreting at a low rate has been proposed, but observational evidence for this in the form of expanding hot gas shells is indirect and limited to radio galaxies at the centres of clusters, which are too rare to explain the vast majority of the quiescent population. Here we report bisymmetric emission features co-aligned with strong ionized-gas velocity gradients from which we infer the presence of centrally driven winds in typical quiescent galaxies that host low-luminosity active nuclei. These galaxies are surprisingly common, accounting for as much as ten per cent of the quiescent population with masses around 2 × 10(10) times that of the Sun. In a prototypical ex le, we calculate that the energy input from the galaxy's low-level active supermassive black hole is capable of driving the observed wind, which contains sufficient mechanical energy to heat ambient, cooler gas (also detected) and thereby suppress star formation.
Publisher: Oxford University Press (OUP)
Date: 06-07-2020
Abstract: We present results from the KMOS Lens-Amplified Spectroscopic Survey (KLASS), an ESO Very Large Telescope (VLT) large program using gravitational lensing to study the spatially resolved kinematics of 44 star-forming galaxies at 0.6 & z & 2.3 with a stellar mass of 8.1 & log(M⋆/M⊙) & 11.0. These galaxies are located behind six galaxy clusters selected from the Hubble Space Telescope Grism Lens-Amplified Survey from Space (GLASS). We find that the majority of the galaxies show a rotating disc, but most of the rotation-dominated galaxies only have a low υ rot/σ0 ratio (median of υrot/σ0 ∼ 2.5). We explore the Tully–Fisher relation by adopting the circular velocity, $V_{\\mathrm{ circ}}=(\\upsilon _{\\mathrm{ rot}}^2+3.4\\sigma _0^2)^{1/2}$, to account for pressure support. We find that our s le follows a Tully–Fisher relation with a positive zero-point offset of +0.18 dex compared to the local relation, consistent with more gas-rich galaxies that still have to convert most of their gas into stars. We find a strong correlation between the velocity dispersion and stellar mass in the KLASS s le. When combining our data to other surveys from the literature, we see an increase of the velocity dispersion with stellar mass at all redshift. We obtain an increase of υrot/σ0 with stellar mass at 0.5 & z & 1.0. This could indicate that massive galaxies settle into regular rotating discs before the low-mass galaxies. For higher redshift (z & 1), we find a weak increase or flat trend. We find no clear trend between the rest-frame UV clumpiness and the velocity dispersion and υrot/σ0. This could suggest that the kinematic properties of galaxies evolve after the clumps formed in the galaxy disc or that the clumps can form in different physical conditions.
Publisher: American Astronomical Society
Date: 07-03-2017
Publisher: Oxford University Press (OUP)
Date: 07-08-2018
Publisher: Cambridge University Press (CUP)
Date: 11-2019
DOI: 10.1017/S1743921319002734
Abstract: We study star formation and metallicity enrichment histories of 24 massive galaxies at 1.6 z 2.5. Deep slitless spectroscopy + imaging data set collected from multiple HST surveys allows robust determination of their SEDs. Our new SED modeling with no functional assumptions on star formation histories revels that 1. most of the s le galaxies have already formed % of their extant masses ∼1.5 Gyr before the time of observed redshifts, with a trend where more massive galaxies form earlier, 2. most of our galaxies already have stellar metallicities compatible with those of local early-type galaxies, and 3. inferred metallicities are on average ∼ 0.25 dex higher than observed gas-phase metallicities of star forming galaxies at the time of their formation. Continuation of low-level star formation, rather than abrupt termination of star forming activity, may explain the observed gap of metallicities.
Publisher: American Astronomical Society
Date: 24-05-2018
Publisher: American Astronomical Society
Date: 03-2022
Abstract: Ram pressure stripping is one of the most efficient mechanisms able to affect the gas reservoir in cluster galaxies, and in the last decades many studies have characterized the properties of stripped galaxies. A definite census of the importance of this process in local clusters is still missing, though. Here, we characterize the fraction of galaxies showing signs of stripping at optical wavelengths, using the data of 66 clusters from the WINGS and OMEGAWINGS surveys. We focus on the infalling galaxy population, and hence only consider blue, bright ( B 18.2), late-type, spectroscopically confirmed cluster members within two virial radii. In addition to “traditional” stripping candidates (SC)—i.e., galaxies showing unilateral debris and tails—we also consider unwinding galaxies (UG) as potentially stripped galaxies. Recent work has indeed unveiled a connection between unwinding features and ram pressure stripping, and even though only integral field studies can inform on how often these features are indeed due to ram pressure, it is important to include them in the global census. We performed a visual inspection of B -band images, and here we release a catalog of 143 UG. SC and UG each represent ∼15%–20% of the inspected s le. If we make the assumption that they both are undergoing ram pressure stripping, we can conclude that, at any given time in the low-z universe, about 35% of the infalling cluster population show signs of stripping in their morphology at optical wavelengths. These fractions depend on color, mass, and morphology, and little on clustercentric distance. Making some rough assumptions regarding the duration of the tail visibility and the time that cluster galaxies can maintain blue colors, we infer that almost all bright blue late-type cluster galaxies undergo a stripping phase during their life, boosting the importance of ram pressure stripping in cluster galaxy evolution.
Publisher: American Astronomical Society
Date: 09-09-2019
Publisher: Oxford University Press (OUP)
Date: 03-10-2023
Publisher: American Astronomical Society
Date: 20-07-2017
Publisher: American Astronomical Society
Date: 09-2023
Publisher: American Astronomical Society
Date: 28-09-2023
Publisher: American Astronomical Society
Date: 04-2019
Publisher: American Astronomical Society
Date: 21-05-2014
Publisher: Oxford University Press (OUP)
Date: 11-09-2021
Abstract: We measure the rate of environmentally driven star formation quenching in galaxies at z ∼ 1, using eleven massive ($M\\approx 2\\times 10^{14}\\, \\mathrm{M}_\\odot$) galaxy clusters spanning a redshift range 1.0 & z & 1.4 from the GOGREEN s le. We identify three different types of transition galaxies: ‘green valley’ (GV) galaxies identified from their rest-frame (NUV − V) and (V − J) colours ‘blue quiescent’ (BQ) galaxies, found at the blue end of the quiescent sequence in (U − V) and (V − J) colour and spectroscopic post-starburst (PSB) galaxies. We measure the abundance of these galaxies as a function of stellar mass and environment. For high-stellar mass galaxies (log M/M⊙ & 10.5) we do not find any significant excess of transition galaxies in clusters, relative to a comparison field s le at the same redshift. It is likely that such galaxies were quenched prior to their accretion in the cluster, in group, filament, or protocluster environments. For lower stellar mass galaxies (9.5 & log M/M⊙ & 10.5) there is a small but significant excess of transition galaxies in clusters, accounting for an additional ∼5–10 per cent of the population compared with the field. We show that our data are consistent with a scenario in which 20–30 per cent of low-mass, star-forming galaxies in clusters are environmentally quenched every Gyr, and that this rate slowly declines from z = 1 to z = 0. While environmental quenching of these galaxies may include a long delay time during which star formation declines slowly, in most cases this must end with a rapid (τ & 1 Gyr) decline in star formation rate.
Publisher: American Astronomical Society
Date: 28-09-2022
Abstract: Jellyfish galaxies, characterized by long filaments of stripped interstellar medium extending from their disks, are the prime laboratories to study the outcomes of ram pressure stripping. At radio wavelengths, they often show unilateral emission extending beyond the stellar disk, and an excess of radio luminosity with respect to that expected from their current star formation rate. We present new 144 MHz images provided by the LOFAR Two-metre Sky Survey for a s le of six galaxies from the GASP survey. These galaxies are characterized by a high global luminosity at 144 MHz (6−27 × 10 22 W Hz −1 ), in excess compared to their ongoing star formation rate. The comparison of radio and H α images smoothed with a Gaussian beam corresponding to ∼10 kpc reveals a sublinear spatial correlation between the two emissions with an average slope of k = 0.50. In their stellar disk we measure k = 0.77, which is close to the radio-to-star formation linear relation. We speculate that, as a consequence of the ram pressure, in these jellyfish galaxies cosmic ray transport is more efficient than in normal galaxies. Radio tails typically have higher radio-to-H α ratios than the disks, thus we suggest that the radio emission is boosted by electrons stripped from the disks. In all galaxies, the star formation rate has decreased by a factor ≤10 within the last ∼10 8 yr. The observed radio emission is consistent with the past star formation, so we propose that this recent decline may be the cause of their radio luminosity-to-star formation rate excess.
Publisher: American Astronomical Society
Date: 11-03-2019
Publisher: American Astronomical Society
Date: 19-01-2010
Publisher: American Astronomical Society
Date: 03-2023
Abstract: Stellar bars have been found to substantially influence the properties of stellar populations in galaxies, affecting their ability to form stars. While this can be easily seen when studying galaxies in relatively isolated environments, such type of analysis requires a higher degree of complexity when cluster galaxies are considered, due to the variety of interactions that can potentially occur in these denser environments. We use IFU MUSE data from the GASP survey to study the combined effect of the presence of a stellar bar and ram pressure, on spatially resolved properties of stellar populations. We have analyzed spatially resolved indicators of both recent star formation rates (SFRs) and average stellar population ages to check for signatures of anomalous central star formation activity, also taking into account the possible presence of nuclear activity. We found an increase in central SFR in ram-pressure-affected galaxies when compared with unperturbed ones. The most extreme cases of increased SFR and central rejuvenation occur in barred galaxies that are at advanced stages of ram pressure stripping. For low-mass barred galaxies affected by ram pressure, the combined effect is the systematic enhancement of the star formation activity as opposed to the case of high-mass galaxies, which present both enhancement and suppression. Barred galaxies that present suppression of their star formation activity also present signatures of nuclear activity. Our results indicate that the combined effect of the presence of a bar and strong perturbation by ram pressure is able to trigger the central star formation activity and probably ignite nuclear activity.
Publisher: American Astronomical Society
Date: 2023
Abstract: We exploit James Webb Space Telescope (JWST) NIRCam observations from the GLASS-JWST-Early Release Science program to investigate galaxy stellar masses at z 7. We first show that JWST observations reduce the uncertainties on the stellar mass by a factor of at least 5–10, when compared with the highest-quality data sets available to date. We then study the UV mass-to-light ratio, finding that galaxies exhibit a a two orders of magnitude range of M / L UV values for a given luminosity, indicative of a broad variety of physical conditions and star formation histories. As a consequence, previous estimates of the cosmic stellar-mass density—based on an average correlation between UV luminosity and stellar mass—can be biased by as much as a factor of ∼6. Our first exploration demonstrates that JWST represents a new era in our understanding of stellar masses at z 7 and, therefore, of the growth of galaxies prior to cosmic reionization.
Publisher: American Astronomical Society
Date: 02-06-2020
Publisher: Oxford University Press (OUP)
Date: 09-2023
Publisher: American Astronomical Society
Date: 16-12-2016
Publisher: American Astronomical Society
Date: 29-06-2018
Publisher: American Astronomical Society
Date: 03-05-2018
Publisher: Oxford University Press (OUP)
Date: 24-05-2019
Publisher: Oxford University Press (OUP)
Date: 03-06-2020
Abstract: We present a detailed analysis of star formation properties of galaxies in a nearby (z ∼ 0.046) young (∼0.6 Gyr) post-merger cluster system A3376, with a moderate merger shock front (vs ∼1630 km s−1 $\\mathcal {M}$ ∼ 2) observed as symmetric radio relics. Exploiting the spectroscopic data from the wide-field OmegaWINGS survey and the associated photometric information, our investigations reveal the plausible effects of the dynamic post-merger environment differing from the high-density cluster environment experienced prior to the merging activity. The remnants of the pre-merger relaxed cluster environment are realized through the existence of passive spiral galaxies located in the central regions of the cluster between the two brightest cluster galaxies. We discover A3376 to contain a population of massive (log (M*/M⊙) & 10) blue regular star-forming spirals in regions of maximum merger shock influence but exhibiting star formation rates similar to those in relaxed clusters at similar epoch. We further discover low-mass (log (M*/M⊙) ≤ 10) late-type blue post-starburst galaxies which could either be formed as a result of rapid quenching of low-mass spirals following the shock-induced star formation or due to the intense surge in the intracluster medium pressures at the beginning of the merger. With the possibility of the merger shock affecting high- and low-mass spirals differently, our results bridge the seemingly contradictory results observed in known merging cluster systems so far and establish that different environmental effects are at play right from pre- to post-merger stages.
Publisher: arXiv
Date: 2022
Publisher: EDP Sciences
Date: 04-2023
DOI: 10.1051/0004-6361/202245532
Abstract: Aims. The demographics of the production and escape of ionizing photons from UV-faint early galaxies is a key unknown that has hindered attempts to discover the primary drivers of reionization. With the advent of JWST, it is finally possible to observe the rest-frame optical nebular emission from in idual sub- L * z 3 galaxies to measure the production rate of ionizing photons, ξ ion . Methods. Here we study a s le of 370 z ∼ 3 − 7 galaxies spanning −23 M UV −15.5 (median M UV ≈ −18) with deep multiband HST and JWST/NIRCam photometry that covers the rest-UV to the optical from the GLASS and UNCOVER JWST surveys. Our s le includes 102 galaxies with Lyman-alpha emission detected in MUSE spectroscopy. We used H α fluxes inferred from NIRCam photometry to estimate the production rate of ionizing photons that do not escape these galaxies, ξ ion (1 − f esc ). Results. We find median log 10 ξ ion (1 − f esc ) = 25.33 ± 0.47, with a broad intrinsic scatter of 0.42 dex, which implies a broad range of galaxy properties and ages in our UV-faint s le. Galaxies detected with Lyman-alpha have ∼0.1 dex higher ξ ion (1 − f esc ), which is explained by their higher H α equivalent width distribution this implies younger ages and higher specific star formation rates and, thus, more O/B stars. We find significant trends of increasing ξ ion (1 − f esc ) with increasing H α equivalent width, decreasing UV luminosity, and decreasing UV slope this implies that the production of ionizing photons is enhanced in young galaxies with assumed low metallicities. We find no significant evidence for sources with very high ionizing escape fractions ( f esc 0.5) in our s le based on their photometric properties, even amongst the Lyman-alpha-selected galaxies. Conclusions. This work demonstrates that considering the full distribution of ξ ion across galaxy properties is important for assessing the primary drivers of reionization.
Publisher: Oxford University Press (OUP)
Date: 03-03-2023
Abstract: We investigate the role of dense environments in suppressing star formation by studying $\\rm \\log _{10}(M_\\star /M_\\odot) \\gt 9.7$ star-forming galaxies in nine clusters from the Local Cluster Survey (0.0137 & z & 0.0433) and a large comparison field s le drawn from the Sloan Digital Sky Survey. We compare the star formation rate (SFR) with stellar mass relation as a function of environment and morphology. After carefully controlling for mass, we find that in all environments, the degree of SFR suppression increases with increasing bulge-to-total (B/T) ratio. In addition, the SFRs of cluster and infall galaxies at a fixed mass are more suppressed than their field counterparts at all values of B/T. These results suggest a quenching mechanism that is linked to bulge growth that operates in all environments and an additional mechanism that further reduces the SFRs of galaxies in dense environments. We limit the s le to B/T ≤ 0.3 galaxies to control for the trends with morphology and find that the excess population of cluster galaxies with suppressed SFRs persists. We model the time-scale associated with the decline of SFRs in dense environments and find that the observed SFRs of the cluster core galaxies are consistent with a range of models including a mechanism that acts slowly and continuously over a long (2–5 Gyr) time-scale, and a more rapid (& Gyr) quenching event that occurs after a delay period of 1–6 Gyr. Quenching may therefore start immediately after galaxies enter clusters.
Publisher: Oxford University Press (OUP)
Date: 24-11-2022
Abstract: Recent observations have shown that the environmental quenching of galaxies at z ∼ 1 is qualitatively different to that in the local Universe. However, the physical origin of these differences has not yet been elucidated. In addition, while low-redshift comparisons between observed environmental trends and the predictions of cosmological hydrodynamical simulations are now routine, there have been relatively few comparisons at higher redshifts to date. Here we confront three state-of-the-art suites of simulations (BAHAMAS+MACSIS, EAGLE+Hydrangea, IllustrisTNG) with state-of-the-art observations of the field and cluster environments from the COSMOS/UltraVISTA and GOGREEN surveys, respectively, at z ∼ 1 to assess the realism of the simulations and gain insight into the evolution of environmental quenching. We show that while the simulations generally reproduce the stellar content and the stellar mass functions of quiescent and star-forming galaxies in the field, all the simulations struggle to capture the observed quenching of satellites in the cluster environment, in that they are overly efficient at quenching low-mass satellites. Furthermore, two of the suites do not sufficiently quench the highest mass galaxies in clusters, perhaps a result of insufficient feedback from AGN. The origin of the discrepancy at low stellar masses ($M_* \\lesssim 10^{10}$ M⊙), which is present in all the simulations in spite of large differences in resolution, feedback implementations, and hydrodynamical solvers, is unclear. The next generation of simulations, which will push to significantly higher resolution and also include explicit modelling of the cold interstellar medium, may help us to shed light on the low-mass tension.
Publisher: Oxford University Press (OUP)
Date: 10-09-2020
Abstract: We study the star formation histories (SFHs) and mass-weighted ages of 331 UVJ-selected quiescent galaxies in 11 galaxy clusters and in the field at 1 & z & 1.5 from the Gemini Observations of Galaxies in Rich Early ENvironments (GOGREEN) survey. We determine the SFHs of in idual galaxies by simultaneously fitting rest-frame optical spectroscopy and broad-band photometry to stellar population models. We confirm that the SFHs are consistent with more massive galaxies having on average earlier formation times. Comparing galaxies found in massive clusters with those in the field, we find galaxies with M* & 1011.3 M⊙ in the field have more extended SFHs. From the SFHs we calculate the mass-weighted ages, and compare age distributions of galaxies between the two environments, at fixed mass. We constrain the difference in mass-weighted ages between field and cluster galaxies to $0.31_{^{-0.33}}^{_{+0.51}}$ Gyr, in the sense that cluster galaxies are older. We place this result in the context of two simple quenching models and show that neither environmental quenching based on time since infall (without pre-processing) nor a difference in formation times alone can reproduce both the average age difference and relative quenched fractions. This is distinctly different from local clusters, for which the majority of the quenched population is consistent with having been environmentally quenched upon infall. Our results suggest that quenched population in galaxy clusters at z & 1 has been driven by different physical processes than those at play at z = 0.
Publisher: Zenodo
Date: 2021
Publisher: American Astronomical Society
Date: 10-2022
Abstract: We present the first rest-frame optical size–luminosity relation of galaxies at z 7, using the NIRCam imaging data obtained by the GLASS James Webb Space Telescope Early Release Science (GLASS-JWST-ERS) program, providing the deepest extragalactic data of the ERS c aign. Our s le consists of 19 photometrically selected bright galaxies with m F444W ≤ 27.8 at 7 z 9 and m F444W 28.2 at z ∼ 9−15. We measure the size of the galaxies in five bands, from rest-frame optical (∼4800 Å) to the UV (∼1600 Å) based on the Sérsic model, and analyse the size–luminosity relation as a function of wavelength. Remarkably, the data quality of the NIRCam imaging is sufficient to probe the half-light radius r e down to ∼100 pc at z 7. Given the limited s le size and magnitude range, we first fix the slope to that observed for larger s les in rest-frame UV using Hubble Space Telescope s les. The median size r 0 at the reference luminosity M = −21 decreases slightly from rest-frame optical (600 ± 80 pc) to UV (450 ± 130 pc). We then refit the size–luminosity relation allowing the slope to vary. The slope is consistent with β ∼ 0.2 for all bands except F150W, where we find a marginally steeper slope of β = 0.53 ± 0.15. The steep UV slope is mainly driven by the smallest and faintest galaxies. If confirmed by larger s les, it implies that the UV size–luminosity relation breaks toward the faint end, as suggested by lensing studies.
Publisher: Oxford University Press (OUP)
Date: 10-2023
Publisher: American Astronomical Society
Date: 05-2023
Abstract: We present a rest-frame optical morphological analysis of galaxies observed with the NIRCam imager on the James Webb Space Telescope (JWST) as part of the GLASS-JWST Early Release Science program. We select 388 sources at redshifts 0.8 z 5.4 and use the seven 0.9–5 μ m NIRCam filters to generate rest-frame gri composite color images, and conduct visual morphological classification. Compared to Hubble Space Telescope (HST)–based work we find a higher incidence of disks and bulges than expected at z 1.5, revealed by rest-frame optical imaging. We detect 123 clear disks (58 at z 1.5) of which 76 have bulges. No evolution of bulge fraction with redshift is evident: 61% at z 2 ( N = 110) versus 60% at z ≥ 2 ( N = 13). A stellar mass dependence is evident, with bulges visible in 80% of all disk galaxies with mass 9.5 M ⊙ ( N = 41) but only 52% at M 10 9.5 M ⊙ ( N = 82). We supplement visual morphologies with nonparametric measurements of Gini and asymmetry coefficients in the rest-frame i band. Our sources are more asymmetric than local galaxies, with slightly higher Gini values. When compared to high- z rest-frame ultraviolet measurements with HST, JWST shows more regular morphological types such as disks, bulges, and spiral arms at z 1.5, with smoother (i.e., lower Gini) and more symmetrical light distributions.
Publisher: American Astronomical Society
Date: 05-2023
Abstract: We combine JWST/NIRCam imaging and MUSE data to characterize the properties of galaxies in different environmental conditions in the cluster Abell2744 ( z = 0.3064) and in its immediate surroundings. We investigate how galaxy colors, morphology, and star-forming fractions depend on wavelength and on different parameterizations of environment. Our most striking result is the discovery of a “red excess” population in F200W−F444W colors in both the cluster regions and the field. These galaxies have normal F115W−F150W colors but are up to 0.8 mag redder than red sequence galaxies in F200W−F444W. They also have rather blue rest-frame B − V colors. Galaxies in the field and at the cluster virial radius are overall characterized by redder colors, but galaxies with the largest color deviations are found in the field and in the cluster core. Several results suggest that mechanisms taking place in these regions might be more effective in producing these colors. Looking at their morphology, many cluster galaxies show signatures consistent with ram pressure stripping, while field galaxies have features resembling interactions and mergers. Our hypothesis is that these galaxies are characterized by dust-enshrouded star formation: a JWST/NIRSpec spectrum for one of the galaxies is dominated by a strong PAH at 3.3 μ m, suggestive of dust-obscured star formation. Larger spectroscopic s les are needed to understand whether the color excess is due exclusively to dust-obscured star formation, as well as the role of environment in triggering it.
Publisher: American Astronomical Society
Date: 03-2022
Abstract: We present the results of a Very Large Array H i imaging survey aimed at understanding why some galaxies develop long extraplanar H α tails, becoming extreme jellyfish galaxies. The observations are centered on five extreme jellyfish galaxies optically selected from the WINGS and OMEGAWINGS surveys and confirmed to have long H α tails through MUSE observations. Each galaxy is located in a different cluster. In the observations, there are in total 88 other spiral galaxies within the field of view (40′ × 40′) and observed bandwidth (6500 km s −1 ). We detect 13 of these 88 spirals, plus one uncataloged spiral, with H i masses ranging from 1 to 7 × 10 9 M ⊙ . Many of these detections have extended H i disks, two show direct evidence for ram pressure stripping, and others are possibly affected by tidal forces and/or ram pressure stripping. We stack the 75 nondetected spiral galaxies and find an average H i mass of 1.9 × 10 8 M ⊙ , which, given their average stellar mass, implies that they are very H i deficient. Comparing the extreme jellyfish galaxies to the other disk galaxies, we find that they are at smaller projected distance from the cluster center, and have a higher stellar mass and higher relative velocity than all other H i detections and most nondetections. We conclude that the high stellar mass allows extreme jellyfish galaxies to fall deeply into the cluster before being stripped, and the surrounding ICM pressure gives rise to their spectacular star-forming tails.
Publisher: American Astronomical Society
Date: 19-12-2014
Publisher: Oxford University Press (OUP)
Date: 28-10-2020
Abstract: We present the first study of the effect of ram pressure ‘unwinding’ the spiral arms of cluster galaxies. We study 11 ram-pressure stripped galaxies from GASP (GAs Stripping Phenomena in galaxies) in which, in addition to more commonly observed ‘jellyfish’ features, dislodged material also appears to retain the original structure of the spiral arms. Gravitational influence from neighbours is ruled out and we compare the s le with a control group of undisturbed spiral galaxies and simulated stripped galaxies. We first confirm the unwinding nature, finding that the spiral arm pitch angle increases radially in 10 stripped galaxies and also simulated face-on and edge-on stripped galaxies. We find only younger stars in the unwound component, while older stars in the disc remain undisturbed. We compare the morphology and kinematics with simulated ram-pressure stripping galaxies, taking into account the estimated inclination with respect to the intracluster medium (ICM) and find that in edge-on stripping, unwinding can occur due to differential ram pressure caused by the disc rotation, causing stripped material to slow and ‘pile up’. In face-on cases, gas removed from the outer edges falls to higher orbits, appearing to ‘unwind’. The pattern is fairly short-lived (& .5 Gyr) in the stripping process, occurring during first infall and eventually washed out by the ICM wind into the tail of the jellyfish galaxy. By comparing simulations with the observed s le, we find that a combination of face-on and edge-on ‘unwinding’ effects is likely to be occurring in our galaxies as they experience stripping with different inclinations with respect to the ICM.
Publisher: EDP Sciences
Date: 06-2021
DOI: 10.1051/0004-6361/202140564
Abstract: Context. The study of galaxy cluster mass profiles ( M ( r )) provides constraints on the nature of dark matter and on physical processes affecting the mass distribution. The study of galaxy cluster velocity anisotropy profiles ( β ( r )) informs the orbits of galaxies in clusters, which are related to their evolution. The combination of mass profiles and velocity anisotropy profiles allows us to determine the pseudo phase-space density profiles ( Q ( r )) numerical simulations predict that these profiles follow a simple power law in cluster-centric distance. Aims. We determine the mass, velocity anisotropy, and pseudo phase-space density profiles of clusters of galaxies at the highest redshifts investigated in detail to date. Methods. We exploited the combination of the GOGREEN and GCLASS spectroscopic data-sets for 14 clusters with mass M 200 ≥ 10 14 M ⊙ at redshifts 0.9 ≤ z ≤ 1.4. We constructed an ensemble cluster by stacking 581 spectroscopically identified cluster members with stellar mass M ⋆ ≥ 10 9.5 M ⊙ . We used the MAMPOSSt method to constrain several M ( r ) and β ( r ) models, and we then inverted the Jeans equation to determine the ensemble cluster β ( r ) in a non-parametric way. Finally, we combined the results of the M ( r ) and β ( r ) analysis to determine Q ( r ) for the ensemble cluster. Results. The concentration c 200 of the ensemble cluster mass profile is in excellent agreement with predictions from Λ cold dark matter (ΛCDM) cosmological numerical simulations, and with previous determinations for clusters of similar mass and at similar redshifts, obtained from gravitational lensing and X-ray data. We see no significant difference between the total mass density and either the galaxy number density distributions or the stellar mass distribution. Star-forming galaxies are spatially significantly less concentrated than quiescent galaxies. The orbits of cluster galaxies are isotropic near the center and more radial outside. Star-forming galaxies and galaxies of low stellar mass tend to move on more radially elongated orbits than quiescent galaxies and galaxies of high stellar mass. The profile Q ( r ), determined using either the total mass or the number density profile, is very close to the power-law behavior predicted by numerical simulations. Conclusions. The internal dynamics of clusters at the highest redshift probed in detail to date are very similar to those of lower-redshift clusters, and in excellent agreement with predictions of numerical simulations. The clusters in our s le have already reached a high degree of dynamical relaxation.
Publisher: American Astronomical Society
Date: 10-2022
Abstract: We present the results of a first search for galaxy candidates at z ∼ 9–15 on deep seven-band NIRCam imaging acquired as part of the GLASS-James Webb Space Telescope (JWST) Early Release Science Program on a flanking field of the Frontier Fields cluster A2744. Candidates are selected via two different renditions of the Lyman-break technique, isolating objects at z ∼ 9–11, and z ∼ 9–15, respectively, supplemented by photometric redshifts obtained with two independent codes. We find five color-selected candidates at z 9, plus one additional candidate with photometric redshift z phot ≥ 9. In particular, we identify two bright candidates at M UV ≃ −21 that are unambiguously placed at z ≃ 10.6 and z ≃ 12.2, respectively. The total number of galaxies discovered at z 9 is in line with the predictions of a nonevolving luminosity function. The two bright ones at z 10 are unexpected given the survey volume, although cosmic variance and small number statistics limits general conclusions. This first search demonstrates the unique power of JWST to discover galaxies at the high-redshift frontier. The candidates are ideal targets for spectroscopic follow-up in Cycle-2.
Publisher: American Astronomical Society
Date: 11-09-2017
Publisher: American Astronomical Society
Date: 02-2017
Publisher: American Astronomical Society
Date: 14-10-2015
Publisher: American Astronomical Society
Date: 10-07-2020
Publisher: EDP Sciences
Date: 07-2023
DOI: 10.1051/0004-6361/202346517
Abstract: Context. Wide-field radio continuum observations of galaxy clusters are revealing an increasing number of spiral galaxies hosting tens of kiloparsec-length radio tails produced by the displacement of nonthermal interstellar medium (ISM) by ram pressure. Aims. We present a semi-empirical model for the multifrequency radio continuum emission from ram-pressure-stripped tails based on the pure synchrotron cooling of a radio plasma moving along the stripping direction with a uniform velocity. Methods. We combine LOFAR and uGMRT observations at 144 and 400 MHz to study the flux density and spectral index profiles of the radio tails of seven galaxies in Abell 2255, and use the model to reproduce the flux density and spectral index profiles, and infer the stripped radio plasma velocity. Results. For five out of these seven galaxies, we observe a monotonic decrease in both flux density and spectral index up to 30 kpc from their stellar disk. Our model reproduces the observed trends with a projected radio plasma bulk velocity of between 160 and 430 km s −1 . This result represents the first indirect measurement of the stripped, nonthermal ISM velocity. The observed spectral index trends indicate that the synchrotron cooling is faster than the adiabatic expansion losses, suggesting that the stripped radio plasma can survive for a few tens of million years outside of the stellar disk. This provides a lower limit on the lifetime of the stripped ISM outside of the disk. As a proof of concept, we use the best-fit velocities to constrain the 3D velocity of the galaxies in the cluster to be in the range of 300−1300 km s −1 . We estimate the ram pressure affecting these galaxies to be between 0.1 and 2.9 × 10 −11 erg cm −3 , and measure the inclination between their stellar disk and the ram pressure wind.
Publisher: Oxford University Press (OUP)
Date: 08-05-2014
DOI: 10.1093/MNRAS/STU632
Publisher: American Astronomical Society
Date: 05-02-2020
Publisher: American Astronomical Society
Date: 24-10-2017
Publisher: American Astronomical Society
Date: 30-11-2018
Publisher: EDP Sciences
Date: 08-2020
DOI: 10.1051/0004-6361/202037759
Abstract: We present atomic hydrogen (H I ) observations with the Jansky Very Large Array of one of the jellyfish galaxies in the GAs Stripping Phenomena s le, JO201. This massive galaxy ( M * = 3.5 × 10 10 M ⊙ ) is falling along the line-of-sight towards the centre of a rich cluster ( M 200 ∼ 1.6 × 10 15 M ⊙ , σ cl ∼ 982 ± 55 km s −1 ) at a high velocity ≥3363 km s −1 . Its H α emission shows a ∼40 kpc tail, which is closely confined to its stellar disc and a ∼100 kpc tail extending further out. We find that H I emission only coincides with the shorter clumpy H α tail, while no H I emission is detected along the ∼100 kpc H α tail. In total, we measured an H I mass of M HI = 1.65 × 10 9 M ⊙ , which is about 60% lower than expected based on its stellar mass and stellar surface density. We compared JO201 to another jellyfish in the GASP s le, JO206 (of a similar mass but living in a ten times less massive cluster), and we find that they are similarly H I -deficient. Of the total H I mass in JO201, about 30% lies outside the galaxy disc in projection. This H I fraction is probably a lower limit since the velocity distribution shows that most of the H I is redshifted relative to the stellar disc and could be outside the disc. The global star formation rate (SFR) analysis of JO201 suggests an enhanced star formation for its observed H I content. The observed SFR would be expected if JO201 had ten times its current H I mass. The disc is the main contributor of the high star formation efficiency at a given H I gas density for both galaxies, but their tails also show higher star formation efficiencies compared to the outer regions of field galaxies. Generally, we find that JO201 and JO206 are similar based on their H I content, stellar mass, and star formation rate. This finding is unexpected considering their different environments. A toy model comparing the ram pressure of the intracluster medium (ICM) versus the restoring forces of these galaxies suggests that the ram pressure strength exerted on them could be comparable if we consider their 3D orbital velocities and radial distances relative to the clusters.
Publisher: arXiv
Date: 2022
Publisher: EDP Sciences
Date: 09-2016
Publisher: Oxford University Press (OUP)
Date: 12-11-2020
Publisher: American Astronomical Society
Date: 10-2022
Abstract: We present the reduced images and multiwavelength catalog of the first JWST NIRCam extragalactic observations from the GLASS Early Release Science Program, obtained as coordinated parallels of the NIRISS observations of the Abell 2744 cluster. Images in seven bands (F090W, F115W, F150W, F200W, F277W, F356W, and F444W) have been reduced using an augmented version of the official JWST pipeline we discuss the procedures adopted to remove or mitigate defects in the raw images. We obtain a multiband catalog by means of forced aperture photometry on point-spread function (PSF)-matched images at the position of F444W-detected sources. The catalog is intended to enable early scientific investigations, and it is optimized for faint galaxies it contains 6368 sources, with limiting magnitude 29.7 at 5 σ in F444W. We release both images and catalog in order to allow the community to become familiar with the JWST NIRCam data and evaluate their merit and limitations given the current level of knowledge of the instrument.
Publisher: Oxford University Press (OUP)
Date: 03-02-2020
Abstract: We present a catalogue of 22 755 objects with slitless, optical, Hubble Space Telescope (HST) spectroscopy from the Grism Lens-Amplified Survey from Space (GLASS). The data cover ∼220 sq. arcmin to 7-orbit (∼10 ks) depth in 20 parallel pointings of the Advanced Camera for Survey’s G800L grism. The fields are located 6 arcmin away from 10 massive galaxy clusters in the HFF and CLASH footprints. 13 of the fields have ancillary HST imaging from these or other programs to facilitate a large number of applications, from studying metal distributions at z ∼ 0.5, to quasars at z ∼ 4, to the star formation histories of hundreds of galaxies in between. The spectroscopic catalogue has a median redshift of 〈z〉 = 0.60 with a median uncertainty of $\\Delta z / (1+z)\\lesssim 2{{\\ \\rm per\\ cent}}$ at $F814\\mathit{ W}\\lesssim 23$ AB. Robust continuum detections reach a magnitude fainter. The 5 σ limiting line flux is $f_{\\rm lim}\\approx 5\\times 10^{-17}\\rm ~erg~s^{-1}~cm^{-2}$ and half of all sources have 50 per cent of pixels contaminated at ≲1 per cent. All sources have 1D and 2D spectra, line fluxes/uncertainties and identifications, redshift probability distributions, spectral models, and derived narrow-band emission-line maps from the Grism Redshift and Line Analysis tool (grizli). We provide other basic s le characterizations, show data ex les, and describe sources and potential investigations of interest. All data and products will be available online along with software to facilitate their use.
Publisher: Oxford University Press (OUP)
Date: 08-10-2018
Publisher: American Astronomical Society
Date: 2022
Abstract: Ram pressure stripping is a crucial evolutionary driver for cluster galaxies. It is thought to be able to accelerate the evolution of their star formation, trigger the activity of their central active galactic nucleus (AGN) and the interplay between galactic and environmental gas, and eventually dissipate their gas reservoirs. We explored the outcomes of ram pressure stripping by studying the nonthermal radio emission of the jellyfish galaxy JW100 in the cluster A2626 ( z = 0.055), by combining LOw Frequency Array, MeerKAT, and Very Large Array observations from 0.144 to 5.5 GHz. We studied the integrated spectra of the stellar disk, the stripped tail, and the AGN mapped the spectral index over the galaxy and constrained the magnetic field intensity to between 11 and 18 μ G in the disk and μ G in the tail. The stellar disk radio emission is dominated by a radiatively old plasma, likely related to an older phase of a high star formation rate. This suggests that the star formation was quickly quenched by a factor of 4 in a few 10 7 yr. The radio emission in the tail is consistent with the stripping scenario, where the radio plasma that originally accelerated in the disk is subsequently displaced in the tail. The morphology of the radio and X-ray emissions supports the scenario of the accretion of magnetized environmental plasma onto the galaxy. The AGN nonthermal spectrum indicates that relativistic electron acceleration may have occurred simultaneously with a central ionized gas outflow, thus suggesting a physical connection between the two processes.
Publisher: Oxford University Press (OUP)
Date: 20-02-2023
Abstract: The observed properties of galaxies are strongly dependent on both their total stellar mass and their morphology. Furthermore, the environment is known to play a strong role in shaping them. The galaxy population in the local Universe that is located in virialized clusters is found to be red, poorly star-forming, and mostly composed of early morphological types. Towards a holistic understanding of the mechanisms that drive galaxy evolution, we exploit the spectrophotometric data from the WINGS and OmegaWINGS local galaxy cluster surveys, and study the role of both the local and the large-scale environments. We attempt to disentangle their effects from the intrinsic characteristics of the galaxies, in shaping the star formation activity at fixed morphological type and stellar mass. Using a s le of field galaxies from the same surveys for comparison, we analyse the effects of the environment, embodied by the local density, clustercentric distance, and close neighbours, respectively, on the star formation histories of cluster galaxies. We find that local effects have a more relevant impact on galaxy stellar properties than the large-scale environment, and that morphology needs to be taken into account to pinpoint the mechanisms that are driving the influence of clusters in galaxy evolution.
Publisher: EDP Sciences
Date: 06-2020
DOI: 10.1051/0004-6361/202037754
Abstract: We study the stellar mass functions (SMFs) of star-forming and quiescent galaxies in 11 galaxy clusters at 1.0 z 1.4 drawn from the Gemini Observations of Galaxies in Rich Early ENvironments (GOGREEN) survey. Based on more than 500 h of Gemini/GMOS spectroscopy and deep multi-band photometry taken with a range of observatories, we probe the SMFs down to a stellar mass limit of 10 9.7 M ⊙ (10 9.5 M ⊙ for star-forming galaxies). At this early epoch, the fraction of quiescent galaxies is already highly elevated in the clusters compared to the field at the same redshift. The quenched fraction excess (QFE) represents the fraction of galaxies that would be star-forming in the field but are quenched due to their environment. The QFE is strongly mass dependent, and increases from ∼30% at M ⋆ = 10 9.7 M ⊙ to ∼80% at M ⋆ = 10 11.0 M ⊙ . Nonetheless, the shapes of the SMFs of the two in idual galaxy types, star-forming and quiescent galaxies, are identical between cluster and field to high statistical precision. Nevertheless, along with the different quiescent fractions, the total galaxy SMF is also environmentally dependent, with a relative deficit of low-mass galaxies in the clusters. These results are in stark contrast with findings in the local Universe, and therefore require a substantially different quenching mode to operate at early times. We discuss these results in light of several popular quenching models.
Publisher: American Astronomical Society
Date: 07-04-2020
Publisher: American Astronomical Society
Date: 07-04-2014
Publisher: American Astronomical Society
Date: 22-10-2013
Publisher: American Astronomical Society
Date: 06-2023
Abstract: Cluster galaxies are subject to the ram pressure exerted by the intracluster medium, which can perturb or even strip away their gas while leaving the stars undisturbed. We model the distribution and kinematics of the stars and the molecular gas in four late-type cluster galaxies (JO201, JO204, JO206, and JW100), which show tails of atomic and ionized gas indicative of ongoing ram pressure stripping. We analyze MUSE@VLT data and CO data from the Atacama Large Millimeter Array searching for signatures of radial gas flows, ram pressure stripping, and other perturbations. We find that all galaxies, with the possible exception of JW100, host stellar bars. Signatures of ram pressure are found in JO201 and JO206, which also shows clear indications of ongoing stripping in the molecular disk outskirts. The stripping affects the whole molecular gas disk of JW100. The molecular gas kinematics in JO204 is instead dominated by rotation rather than ram pressure. We also find indications of enhanced turbulence of the molecular gas compared to field galaxies. Large-scale radial flows of molecular gas are present in JO204 and JW100, but more uncertain in JO201 and JO206. We show that our s le follows the molecular gas mass–size relation, confirming that it is essentially independent of environment even for the most extreme cases of stripping. Our findings are consistent with the molecular gas being affected by the ram pressure on different timescales and less severely than the atomic and ionized gas phases, likely because the molecular gas is denser and more gravitationally bound to the galaxy.
Publisher: Springer Science and Business Media LLC
Date: 26-10-2020
Publisher: American Astronomical Society
Date: 20-08-2018
Publisher: Springer Science and Business Media LLC
Date: 08-2017
DOI: 10.1038/NATURE23462
Abstract: When a supermassive black hole at the centre of a galaxy accretes matter, it gives rise to a highly energetic phenomenon: an active galactic nucleus. Numerous physical processes have been proposed to account for the funnelling of gas towards the galactic centre to feed the black hole. There are also several physical processes that can remove gas from a galaxy, one of which is ram-pressure stripping by the hot gas that fills the space between galaxies in galaxy clusters. Here we report that six out of a s le of seven 'jellyfish' galaxies-galaxies with long 'tentacles' of material that extend for dozens of kiloparsecs beyond the galactic disks-host an active nucleus, and two of them also have galactic-scale ionization cones. The high incidence of nuclear activity among heavily stripped jellyfish galaxies may be due to ram pressure causing gas to flow towards the centre and triggering the activity, or to an enhancement of the stripping caused by energy injection from the active nucleus, or both. Our analysis of the galactic position and velocity relative to the cluster strongly supports the first hypothesis, and puts forward ram pressure as another possible mechanism for feeding the central supermassive black hole with gas.
Publisher: American Astronomical Society
Date: 31-05-2023
Abstract: Determining which between projected local density and distance from the cluster center plays a major role in regulating morphological fractions in clusters is a longstanding debate. Reaching a definitive answer will shed light on the main physical mechanisms at play in the most extreme environments. Here we make use of the data from the OmegaWINGS survey, currently the largest survey of clusters in the local universe extending beyond 2 virial radii from the cluster cores, to extend the previous analysis outside the virial radius. Local density and clustercentric distance seems to play different roles for galaxies of different morphology: the fraction of elliptical galaxies mainly depends on local density, suggesting that their formation was linked to the primordial densities, which now correspond to the cluster cores. Only the fraction of low-mass ellipticals shows an anticorrelation with clustercentric distance, suggesting a different origin for these objects. Excluding elliptical galaxies, the relative fraction of S0s and spirals instead depends on local density only far from the cluster cores, while within the virial radius their proportion is regulated by distance, suggesting that cluster-specific processes halt the star formation and transform Sp galaxies into S0s. This interpretation is supported by literature results on the kinematical analysis of early- and late-type galaxies, according to which fast and slow rotators have distinct dependencies on halo mass and local density.
Publisher: American Astronomical Society
Date: 20-08-2018
Publisher: American Astronomical Society
Date: 20-07-2017
Publisher: American Astronomical Society
Date: 05-2022
Abstract: We present results from MUSE spatially resolved spectroscopy of 21 post-starburst galaxies in the centers of eight clusters from z ∼ 0.3 to z ∼ 0.4. We measure spatially resolved star formation histories (SFHs), the time since quenching ( t Q ), and the fraction of stellar mass assembled in the past 1.5 Gyr ( μ 1.5 ). The SFHs display a clear enhancement of star formation prior to quenching for 16 out of 21 objects, with at least 10% (and up to %) of the stellar mass being assembled in the past 1.5 Gyr and t Q ranging from less than 100 to ∼800 Myr. By mapping t Q and μ 1.5 , we analyze the quenching patterns of the galaxies. Most galaxies in our s le have quenched their star formation from the outside in or show a side-to-side/irregular pattern, both consistent with quenching by ram pressure stripping. Only three objects show an inside-out quenching pattern, all of which are at the high-mass end of our s le. At least two of them currently host an active galactic nucleus. In two post-starbursts, we identify tails of ionized gas indicating that these objects had their gas stripped by ram pressure very recently. Post-starburst features are also found in the stripped regions of galaxies undergoing ram pressure stripping in the same clusters, confirming the link between these classes of objects. Our results point to ram pressure stripping as the main driver of fast quenching in these environments, with active galactic nuclei playing a role at high stellar masses.
Publisher: American Astronomical Society
Date: 07-08-2020
Publisher: SPIE
Date: 30-08-2022
DOI: 10.1117/12.2629001
Publisher: American Astronomical Society
Date: 12-2022
Abstract: We investigate the blue and optical rest-frame sizes ( λ ≃ 2300–4000 Å) of three compact star-forming regions in a galaxy at z = 4 strongly lensed (×30, ×45, and ×100) by the Hubble Frontier Field galaxy cluster A2744 using GLASS-ERS James Webb Space Telescope (JWST)/NIRISS imaging at 1.15 μ m, 1.50 μ m, and 2.0 μ m with a point-spread function ≲0.″1. In particular, the Balmer break is probed in detail for all multiply imaged sources of the system. With ages of a few tens of Myr, stellar masses in the range (0.7–4.0) ×10 6 M ⊙ and optical/ultraviolet effective radii spanning the interval 3 R eff 20 pc, such objects are currently the highest-redshift (spectroscopically confirmed) gravitationally bound young massive star clusters (YMCs), with stellar mass surface densities resembling those of local globular clusters. Optical (4000 Å, JWST-based) and ultraviolet (1600 Å, Hubble Space Telescope–based) sizes are fully compatible. The contribution to the ultraviolet underlying continuum emission (1600 Å) is ∼30%, which decreases by a factor of 2 in the optical for two of the YMCs (∼4000 Å rest-frame), reflecting the young ages ( Myr) inferred from the spectral energy distribution fitting and supported by the presence of high-ionization lines secured with the Very Large Telescope/MUSE. Such bursty forming regions enhance the specific star formation rate of the galaxy, which is ≃10 Gyr −1 . This galaxy would be among the extreme analogs observed in the local universe having a high star formation rate surface density and a high occurrence of massive stellar clusters in formation.
Publisher: American Astronomical Society
Date: 23-02-2017
Publisher: American Astronomical Society
Date: 10-2022
Abstract: We present the first search for z ≥ 7, continuum-confirmed Lyman break sources with NIRISS/WFS spectroscopy over the Abell 2744 Frontier Fields cluster, as part of the GLASS-JWST-ERS survey. With ∼15 hr of preimaging and multiangle grism exposures in the F115W, F150W, and F200W filters, we describe the general data handling (i.e., reduction, cleaning, modeling, and extraction processes) and analysis for the GLASS-JWST survey. We showcase the power of JWST to peer deep into reionization, when most intergalactic hydrogen is neutral, by confirming two galaxies at z = 8.04 ± 0.15 and z = 7.90 ± 0.13 by means of their Lyman breaks. Fainter continuum spectra are observed in both the F150W and F200W bands, indicative of blue (−1.69 and −1.33) UV slopes and moderately bright absolute magnitudes (−20.37 and −19.68 mag). We do not detect strong Ly α in either galaxy, but do observe tentative (∼2.7–3.8 σ ) He ii λ 1640 Å, O iii ] λλ 1661,1666 Å, and N iii ] λλ 1747,1749 Å line emission in one, suggestive of low-metallicity, star-forming systems with possible nonthermal contributions. These novel observations provide a first look at the extraordinary potential of JWST/NIRISS for confirming representative s les of bright z ≥ 7 sources in the absence of strong emission lines, and gain unprecedented insight into their contributions toward cosmic reionization.
Publisher: SPIE
Date: 13-12-2020
DOI: 10.1117/12.2561251
Publisher: American Astronomical Society
Date: 06-2023
Abstract: Exploiting broad- and narrowband images of the Hubble Space Telescope from the near-UV to I -band rest frame, we study the star-forming clumps of six galaxies of the GASP s le undergoing strong ram pressure stripping. Clumps are detected in H α and near-UV, tracing star formation on different timescales. We consider clumps located in galaxy disks and stripped tails and formed in stripped gas but still close to the disk, called extraplanar. We detect 2406 H α -selected clumps (1708 in disks, 375 in extraplanar regions, and 323 in tails) and 3745 UV-selected clumps (2021 disk, 825 extraplanar, and 899 tail clumps). Only ∼15% of star-forming clumps are spatially resolved, meaning that most are smaller than ∼140 pc. We study the luminosity and size distribution functions (LDFs and SDFs, respectively) and the luminosity–size relation. The average LDF slope is 1.79 ± 0.09, while the average SDF slope is 3.1 ± 0.5. The results suggest that the star formation is turbulence-driven and scale-free, as in main-sequence galaxies. All of the clumps, whether they are in the disks or tails, have an enhanced H α luminosity at a given size, compared to the clumps in main-sequence galaxies. Indeed, their H α luminosity is closer to that of clumps in starburst galaxies, indicating that ram pressure is able to enhance the luminosity. No striking differences are found among disk and tail clumps, suggesting that the different environments in which they are embedded play a minor role in influencing the star formation.
Publisher: American Astronomical Society
Date: 07-2023
Abstract: We present a new high-precision, JWST-based, strong-lensing model for the galaxy cluster Abell 2744 at z = 0.3072. By combining the deep, high-resolution JWST imaging from the Grism Lens Amplified Survey from Space–JWST and Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization programs and a Director’s Discretionary Time program, with newly obtained Very Large Telescope/Multi Unit Spectroscopic Explorer (MUSE) data, we identify 32 multiple images from 11 background sources lensed by two external subclusters at distances of ∼160″ from the main cluster. The new MUSE observations enable the first spectroscopic confirmation of a multiple-image system in the external clumps. Moreover, the reanalysis of the spectrophotometric archival and JWST data yields 27 additional multiple images in the main cluster. The new lens model is constrained by 149 multiple images (∼66% more than in our previous model) covering an extended redshift range between 1.03 and 9.76. The subhalo mass component of the cluster includes 177 member galaxies down to m F160W = 21, of which 163 are spectroscopically confirmed. Internal velocity dispersions are measured for 85 members. The new lens model is characterized by a remarkably low scatter between the predicted and observed positions of the multiple images (0.″43). This precision is unprecedented given the large multiple-image s le, the complexity of the cluster mass distribution, and the large modeled area. The improved precision and resolution of the cluster total mass distribution provides a robust magnification map over a ∼30 arcmin 2 area, which is critical for inferring the intrinsic physical properties of the highly magnified, high- z sources. The lens model and the new MUSE redshift catalog are released with this publication.
Publisher: American Astronomical Society
Date: 21-01-2021
Publisher: Oxford University Press (OUP)
Date: 30-09-2020
Abstract: We present the first public data release of the GOGREEN (Gemini Observations of Galaxies in Rich Early Environments) and GCLASS (Gemini CLuster Astrophysics Spectroscopic Survey) surveys of galaxies in dense environments, spanning a redshift range 0.8 & z & 1.5. The surveys consist of deep, multiwavelength photometry and extensive Gemini GMOS spectroscopy of galaxies in 26 overdense systems ranging in halo mass from small groups to the most massive clusters. The objective of both projects was primarily to understand how the evolution of galaxies is affected by their environment, and to determine the physical processes that lead to the quenching of star formation. There was an emphasis on obtaining unbiased spectroscopy over a wide stellar mass range (M ≳ 2 × 1010 M⊙), throughout and beyond the cluster virialized regions. The final spectroscopic s le includes 2771 unique objects, of which 2257 have reliable spectroscopic redshifts. Of these, 1704 have redshifts in the range 0.8 & z & 1.5, and nearly 800 are confirmed cluster members. Imaging spans the full optical and near-infrared wavelength range, at depths comparable to the UltraVISTA survey, and includes Hubble Space Telescope/Wide Field Camera 3 F160W (GOGREEN) and F140W (GCLASS). This data release includes fully reduced images and spectra, with catalogues of advanced data products including redshifts, line strengths, star formation rates, stellar masses, and rest-frame colours. Here, we present an overview of the data, including an analysis of the spectroscopic completeness and redshift quality.
Publisher: American Astronomical Society
Date: 30-11-2015
Publisher: American Astronomical Society
Date: 31-08-2022
Abstract: X-ray studies of jellyfish galaxies opened a window into the physics of the interplay between the intracluster medium (ICM) and interstellar medium (ISM). In this paper, we present the study of an archival Chandra observation of the GASP jellyfish galaxy JO194. We observe X-ray emission extending from the stellar disk to the unwinding spiral arms with an average temperature of kT = 0.79 ± 0.03 keV. To investigate the origin of the X-ray emission, we compare the observed X-ray luminosities with those expected from the star formation rates (SFRs) obtained from H α emission. We estimate an X-ray luminosity excess of a factor ∼2–4 with respect to the SF therefore, we conclude that SF is not the main event responsible for the extended X-ray emission of JO194. The metallicity in the spiral arms ( Z = 0.24 − 0.12 + 0.19 Z ⊙ ) is consistent with that of the ICM around JO194 ( Z = 0.35 ± 0.07) thus, we suggest that ICM radiative cooling dominates the X-ray emission of the arms. We speculate that the X-ray plasma results from the ISM‒ICM interplay, although the nature of this interplay is still mostly unknown. Finally, we observe that the X-ray properties of JO194 are consistent with those of two other GASP galaxies with different stellar mass, phase-space conditions in their hosting clusters, and local ICM conditions. We suggest that the conditions required to induce extended X-ray emission in jellyfish galaxies are established at the beginning of the stripping, and they can persist on long timescales so that galaxies in different clusters and evolutionary stages can present a similar extended X-ray emission.
Publisher: American Astronomical Society
Date: 04-2023
Abstract: The JWST observations of high-redshift galaxies are used to measure their star formation histories—the buildup of stellar mass in the earliest galaxies. Here we use a novel analysis program, SEDz*, to compare near-IR spectral energy distributions for galaxies with redshifts 5 z 7 to combinations of stellar population templates evolved from z = 12. We exploit NIRCam imaging in seven wide bands covering 1–5 μ m taken in the context of the GLASS-JWST-ERS program and use SEDz* to solve for well-constrained star formation histories for 24 exemplary galaxies. In this first look, we find a variety of histories, from long, continuous star formation over 5 z 12 to short but intense starbursts, sometimes repeating, and, most commonly, contiguous mass buildup lasting ∼0.5 Myr, possibly the seeds of today’s typical M * galaxies.
Publisher: American Astronomical Society
Date: 12-01-2016
Publisher: American Astronomical Society
Date: 10-2021
Publisher: American Astronomical Society
Date: 07-11-2016
Publisher: American Astronomical Society
Date: 2023
Abstract: We present the serendipitous discovery of a late T-type brown dwarf candidate in JWST NIRCam observations of the Early Release Science Abell 2744 parallel field. The discovery was enabled by the sensitivity of JWST at 4 μ m wavelengths and the panchromatic 0.9–4.5 μ m coverage of the spectral energy distribution. The unresolved point source has magnitudes F115W = 27.95 ± 0.15 and F444W = 25.84 ± 0.01 (AB), and its F115W−F444W and F356W−F444W colors match those expected for other known T dwarfs. We can exclude it as a reddened background star, high redshift quasar, or a very high redshift galaxy. Comparison with stellar atmospheric models indicates a temperature of T eff ≈ 650 K and surface gravity log g ≈ 5.25 , implying a mass of 0.03 M ⊙ and age of 5 Gyr. We estimate the distance of this candidate to be 570–720 pc in a direction perpendicular to the Galactic plane, making it a likely thick disk or halo brown dwarf. These observations underscore the power of JWST to probe the very low-mass end of the substellar mass function in the Galactic thick disk and halo.
Publisher: American Astronomical Society
Date: 24-11-2014
Publisher: American Astronomical Society
Date: 06-09-2019
Publisher: American Astronomical Society
Date: 07-2023
Abstract: We present images and a multiwavelength photometric catalog based on all of the JWST NIRCam observations obtained to date in the region of the Abell 2744 galaxy cluster. These data come from three different programs, namely, the GLASS-JWST Early Release Science Program, UNCOVER, and the Director’s Discretionary Time program 2756. The observed area in the NIRCam wide-band filters—covering the central and extended regions of the cluster, as well as new parallel fields—is 46.5 arcmin 2 in total. All images in eight bands (F090W, F115W, F150W, F200W, F277W, F356W, F410M, and F444W) have been reduced adopting the latest calibration and reference files available. Data reduction has been performed using an augmented version of the official JWST pipeline, with improvements aimed at removing or mitigating defects in the raw images and improving the background subtraction and photometric accuracy. We obtain an F444W-detected multiband catalog, including all NIRCam and available Hubble Space Telescope data, adopting forced-aperture photometry on point-spread-function-matched images. The catalog is intended to enable early scientific investigations and is optimized for the study of faint galaxies it contains 24,389 sources, with a 5 σ limiting magnitude in the F444W band ranging from 28.5 AB to 30.5 AB, as a result of the varying exposure times of the surveys that observed the field. We publicly release the reduced NIRCam images, associated multiwavelength catalog, and the code adopted for 1/ f noise removal with the aim of aiding users in familiarizing themselves with JWST NIRCam data and identifying suitable targets for follow-up observations.
Publisher: EDP Sciences
Date: 28-01-2013
Publisher: American Astronomical Society
Date: 11-01-2018
Publisher: Oxford University Press (OUP)
Date: 30-06-2023
Abstract: We present a serendipitously detected system consisting of an S0/a galaxy, which we refer to as the ‘Kite,’ and a highly collimated tail of gas and stars that extends over 380 kpc and contains pockets of star formation. In its length, narrowness, and linearity the Kite’s tail is an extreme ex le relative to known tails. The Kite (PGC 1000273) has a companion galaxy, Mrk 0926 (PGC 070409), which together comprise a binary galaxy system in which both galaxies host active galactic nuclei. Despite this systems being previously searched for signs of tidal interactions, the tail had not been discovered prior to our identification as part of the validation process of the SMUDGes survey for low surface brightness galaxies. We confirm the kinematic association between various H α knots along the tail, a small galaxy, and the Kite galaxy using optical spectroscopy obtained with the Magellan telescope and measure a velocity gradient along the tail. The Kite shares characteristics common to those formed via ram pressure stripping (‘jellyfish’ galaxies) and formed via tidal interactions. However, both scenarios face significant challenges that we discuss, leaving open the question of how such an extreme tail formed. We propose that the tail resulted from a three-body interaction from which the lowest mass galaxy was ejected at high velocity.
Publisher: Oxford University Press (OUP)
Date: 27-07-2018
Publisher: SPIE-Intl Soc Optical Eng
Date: 06-09-2022
Publisher: Oxford University Press (OUP)
Date: 03-11-2021
Abstract: We investigate the role of environment on star formation rates (SFRs) of galaxies at various cosmic densities in well-studied clusters. We present the star-forming main sequence for 163 galaxies in four EDisCS clusters in the range 0.4 & z & 0.7. We use Hubble Space Telescope/Wide Field Camera 3 observations of the H α emission line to span three distinct local environments: the cluster core, infall region, and external field galaxies. The main sequence defined from our observations is consistent with other published H α distributions at similar redshifts but differs from those derived from star formation tracers such as 24 $\\, \\mu$m. We find that the Hα-derived SFRs for the 67 galaxies with stellar masses greater than the mass-completeness limit of M* & 109.75 M⊙ show little dependence on environment. At face value, the similarities in the SFR distributions in the three environments may indicate that the process of finally shutting down star formation is rapid, however, the depth of our data and size of our s le make it difficult to conclusively test this scenario. Despite having significant H α emission, 21 galaxies are classified as UVJ-quiescent and may represent a demonstration of the quenching of star formation caught in the act.
Publisher: EDP Sciences
Date: 11-2017
Publisher: American Astronomical Society
Date: 02-09-2015
Publisher: American Astronomical Society
Date: 14-03-2027
Abstract: We present a new approach for observationally constraining where the tails of Jellyfish (JF) galaxies in groups and clusters first appear and how long they remain visible for with respect to the moment of their orbital pericenter. This is accomplished by measuring the distribution of their tail directions, with respect to their host centers, and their distribution in a projected velocity–radius phase-space diagram. We then model these observed distributions using a fast and flexible approach, where JF tails are painted onto dark matter halos, according to a simple parameterized prescription, before a Bayesian analysis is performed to estimate the parameters. We demonstrate the effectiveness of our approach using observational mocks, then apply it to a known observational s le of 106 JF galaxies, with radio-continuum tails located inside 68 hosts such as groups and clusters. We find that, typically, the radio-continuum tails become visible on first infall, when the galaxy reaches roughly three-quarters of r 200 , and the tails remain visible for a few hundred Myr after pericenter passage. Lower-mass galaxies in more massive hosts tend to form visible tails further out and their tails disappear more quickly after pericenter. We argue that this indicates that they are more sensitive to ram pressure stripping. With upcoming large-area surveys of JF galaxies in progress, this is a promising new method for constraining the environmental conditions in which visible JF tails exist.
Publisher: American Astronomical Society
Date: 20-07-2017
Publisher: American Astronomical Society
Date: 05-06-2019
Publisher: American Astronomical Society
Date: 03-2023
Abstract: Star-forming, H α -emitting clumps are found embedded in the gaseous tails of galaxies undergoing intense ram pressure stripping in galaxy clusters, so-called jellyfish galaxies. These clumps offer a unique opportunity to study star formation under extreme conditions, in the absence of an underlying disk and embedded within the hot intracluster medium. Yet, a comprehensive, high-spatial-resolution study of these systems is missing. We obtained UVIS/Hubble Space Telescope (HST) data to observe the first statistical s le of clumps in the tails and disks of six jellyfish galaxies from the GASP survey we used a combination of broadband (UV to I) filters and a narrowband H α filter. HST observations are needed to study the sizes, stellar masses, and ages of the clumps and their clustering hierarchy. These observations will be used to study the clump scaling relations and the universality of the star formation process, and to verify whether a disk is irrelevant, as hinted at by results from jellyfish galaxies. This paper presents the observations, data reduction strategy, and some general results based on the preliminary data analysis. The high spatial resolution of UVIS gives an unprecedentedly sharp view of the complex structure of the inner regions of the galaxies and of the substructures in the galaxy disks. We found clear signatures of stripping in regions very close in projection to the galactic disk. The star-forming regions in the stripped tails are extremely bright and compact and we did not detect a significant number of star-forming clumps in regions where MUSE did not detect any. The paper finally presents the development plan for the project.
Publisher: American Astronomical Society
Date: 11-2021
Abstract: Hydrodynamical simulations show that the ram pressure stripping in galaxy clusters fosters a strong interaction between stripped interstellar medium (ISM) and the surrounding medium, with the possibility of intracluster medium (ICM) cooling into cold gas clouds. Exploiting the MUSE observation of three jellyfish galaxies from the GAs Stripping Phenomena in galaxies with MUSE (GASP) survey, we explore the gas metallicity of star-forming clumps in their gas tails. We find that the oxygen abundance of the stripped gas decreases as a function of the distance from the parent galaxy disk the observed metallicity profiles indicate that more than 40% of the most metal-poor stripped clouds are constituted by cooled ICM, in qualitative agreement with simulations that predict mixing between the metal-rich ISM and the metal-poor ICM.
Publisher: SPIE
Date: 30-08-2022
DOI: 10.1117/12.2627640
Publisher: Oxford University Press (OUP)
Date: 04-03-2020
Abstract: We present results on the environmental dependence of the star-forming galaxy main sequence in 11 galaxy cluster fields at 1.0 & z & 1.5 from the Gemini Observations of Galaxies in Rich Early Environments Survey (GOGREEN) survey. We use a homogeneously selected s le of field and cluster galaxies whose membership is derived from dynamical analysis. Using [$\\rm{O{\\small II}}$]-derived star formation rates (SFRs), we find that cluster galaxies have suppressed SFRs at fixed stellar mass in comparison to their field counterparts by a factor of 1.4 ± 0.1 (∼3.3σ) across the stellar mass range: 9.0 & log (M*/M⊙) & 11.2. We also find that this modest suppression in the cluster galaxy star-forming main sequence is mass and redshift dependent: the difference between cluster and field increases towards lower stellar masses and lower redshift. When comparing the distribution of cluster and field galaxy SFRs to the star-forming main sequence, we find an overall shift towards lower SFRs in the cluster population, and note the absence of a tail of high SFR galaxies as seen in the field. Given this observed suppression in the cluster galaxy star-forming main sequence, we explore the implications for several scenarios such as formation time differences between cluster and field galaxies, and environmentally induced star formation quenching and associated time-scales.
Publisher: Oxford University Press (OUP)
Date: 14-09-2018
Publisher: American Astronomical Society
Date: 16-07-2020
Publisher: EDP Sciences
Date: 04-2023
DOI: 10.1051/0004-6361/202345866
Abstract: The escape fraction of Lyman-continuum (LyC) photons ( f esc ) is a key parameter for determining the sources of cosmic reionization at z ≥ 6. At these redshifts, owing to the opacity of the intergalactic medium, the LyC emission cannot be measured directly. However, LyC leakers during the epoch of reionization could be identified using indirect indicators that have been extensively tested at low and intermediate redshifts. These include a high [O III ]/[O II ] flux ratio, high star-formation surface density, and compact sizes. In this work, we present observations of 29 4.5 ≤ z ≤ 8 gravitationally lensed galaxies in the Abell 2744 cluster field. From a combined analysis of JWST-NIRSpec and NIRCam data, we accurately derived their physical and spectroscopic properties: our galaxies have low masses (log( M ⋆ )∼8.5), blue UV spectral slopes ( β ∼ −2.1), compact sizes ( r e ∼ 0.3 − 0.5 kpc), and high [O III ]/[O II ] flux ratios. We confirm that these properties are similar to those characterizing low-redshift LyC leakers. Indirectly inferring the fraction of escaping ionizing photons, we find that more than 80% of our galaxies have predicted f esc values larger than 0.05, indicating that they would be considered leakers. The average predicted f esc value of our s le is 0.12, suggesting that similar galaxies at z ≥ 6 have provided a substantial contribution to cosmic reionization.
Publisher: EDP Sciences
Date: 08-2012
Publisher: Oxford University Press (OUP)
Date: 06-09-2022
Abstract: We present MeerKAT H i observations of six jellyfish candidate galaxies (JFCGs) in the galaxy cluster, A2626. Two of the six galaxies JW100 and JW103, which were identified as JFCGs from B-band images, are confirmed as jellyfish galaxies (JFGs). Both of the JFGs have low H i content, reside in the cluster core, and move at very high velocities (∼ 3σcl). The other JFCGs, identified as non-jellyfish galaxies, are H i rich, with H i morphologies revealing warps, asymmetries, and possible tidal interactions. Both the A2626 JFGs and three other confirmed JFGs from the GASP s le show that these galaxies are H i stripped but not yet quenched. We detect H i, H α, and CO(2-1) tails of similar extent (∼50 kpc) in JW100. Comparing the multiphase velocity channels, we do not detect any H i or CO(2-1) emission in the northern section of the tail where H α emission is present, possibly due to prolonged interaction between the stripped gas and the intracluster medium. We also observe an anticorrelation between H i and CO(2-1), which hints at an efficient conversion of H i to H2 in the southern part of the tail. We find that both ram-pressure stripping and H i-to-H2 conversion are significant depletion channels for atomic gas. H i-to-H2 conversion is more efficient in the disc than in the tail.
Publisher: Oxford University Press (OUP)
Date: 10-01-2018
DOI: 10.1093/MNRAS/STY085
Publisher: American Astronomical Society
Date: 15-09-2020
Publisher: American Astronomical Society
Date: 17-10-2018
Publisher: Zenodo
Date: 2021
Publisher: American Astronomical Society
Date: 2023
Abstract: How passive galaxies form, and the physical mechanisms which prevent star formation over long timescales, are some of the most outstanding questions in understanding galaxy evolution. The properties of quiescent galaxies over cosmic time provide crucial information to identify the quenching mechanisms. Passive galaxies have been confirmed and studied out to z ∼ 4, but all of these studies have been limited to massive systems (mostly with log ( M star / M ⊙ ) 10.8 ). Using JWST-NIRISS grism slitless spectroscopic data from the GLASS-JWST Early Release Science program, we present spectroscopic confirmation of two quiescent galaxies at z spec = 2.650 − 0.006 + 0.004 and z spec = 2.433 − 0.016 + 0.032 (3 σ errors) with stellar masses of log ( M star / M ⊙ ) = 10.59 − 0.05 + 0.11 and log ( M star / M ⊙ ) = 10.07 − 0.03 + 0.06 (corrected for magnification factors of μ = 2.0 and μ = 2.1, respectively). The latter represents the first spectroscopic confirmation of the existence of low-mass quiescent galaxies at cosmic noon, showcasing the power of JWST to identify and characterize this enigmatic population.
Publisher: Springer Science and Business Media LLC
Date: 17-05-2023
Publisher: Oxford University Press (OUP)
Date: 07-2011
Publisher: American Astronomical Society
Date: 04-2021
Abstract: X-ray studies of jellyfish galaxies play a crucial role in understanding the interactions between the interstellar medium (ISM) and the intracluster medium (ICM). In this paper, we focused on the jellyfish galaxy JO201. By combining archival Chandra observations, Multi Unit Spectroscopic Explorer H α cubes, and maps of the emission fraction of the diffuse ionized gas, we investigated both its high-energy spectral properties and the spatial correlation between its X-ray and optical emissions. The X-ray emission of JO201 is provided by both the Compton-thick active galactic nucleus ( L = 2.7 · 10 41 erg s −1 , not corrected for intrinsic absorption) and an extended component ( L 1.9–4.5 · 10 41 erg s −1 ) produced by a warm plasma ( kT keV), whose luminosity is higher than expected from the observed star formation ( L 3.8 · 10 40 erg s −1 ). The spectral analysis showed that the X-ray emission is consistent with the thermal cooling of hot plasma. These properties are similar to the ones found in other jellyfish galaxies showing extended X-ray emission. A point-to-point analysis revealed that this X-ray emission closely follows the ISM distribution, whereas CLOUDY simulations proved that the ionization triggered by this warm plasma would be able to reproduce the [O i ]/H α excess observed in JO201. We conclude that the galactic X-ray emitting plasma originates on the surface of the ISM as a result of the ICM–ISM interplay. This process would entail the cooling and accretion of the ICM onto the galaxy, which could additionally fuel the star formation, and the emergence of [O i ]/H α excess in the optical spectrum.
Publisher: Oxford University Press (OUP)
Date: 07-02-2019
Publisher: American Astronomical Society
Date: 10-02-2014
Publisher: American Astronomical Society
Date: 10-2023
Publisher: EDP Sciences
Date: 05-2015
Publisher: American Astronomical Society
Date: 04-04-2017
Publisher: American Astronomical Society
Date: 12-2022
Abstract: Wide Field Slitless Spectroscopy (WFSS) provides a powerful tool for detecting strong line emission in star-forming galaxies (SFGs) without the need for target preselection. As part of the GLASS-JWST Early Release Science (ERS) program, we leverage the near-infrared wavelength capabilities of NIRISS (1–2.2 μ m) to observe rest-optical emission lines out to z ∼ 3.4, to a depth and with a spatial resolution higher than ever before (H α to z 2.4 [O iii ]+H β to z 3.4). In this Letter we constrain the rest-frame [O III ] λ 5007 equivalent width (EW) distribution for a s le of 76 1 z 3.4 SFGs in the A2744 Hubble Frontier Field and determine an abundance fraction of extreme emission line galaxies with EW 750Å in our s le to be 12%. We determine a strong correlation between the measured H β and [O III ] λ 5007 EWs, supporting that the high [O III ] λ 5007 EW objects require massive stars in young stellar populations to generate the high-energy photons needed to doubly ionize oxygen. We extracted spectra for objects up to 2 mag fainter in the near-infrared than previous WFSS studies with the Hubble Space Telescope. Thus, this work clearly highlights the potential of JWST/NIRISS to provide high-quality WFSS data sets in crowded cluster environments.
Publisher: Zenodo
Date: 2021
Publisher: Cambridge University Press (CUP)
Date: 08-2016
DOI: 10.1017/S1743921316006876
Abstract: We present the first study of the spatial distribution of star formation in z ~ 0.5 cluster galaxies. The analysis is based on data taken with the Wide Field Camera 3 as part of the Grism Lens-Amplified Survey from Space (GLASS). We illustrate the methodology by focusing on two clusters (MACS0717.5+3745 and MACS1423.8+2404) with different morphologies (one relaxed and one merging) and use foreground and background galaxies as field control s le. The cluster+field s le consists of 42 galaxies with stellar masses in the range 10 8 -10 11 M ⊙ , and star formation rates in the range 1-20 M ⊙ yr −1 . In both environments, Hα is more extended than the rest-frame UV continuum in 60% of the cases, consistent with diffuse star formation and inside out growth. The Hα emission appears more extended in cluster galaxies than in the field, pointing perhaps to ionized gas being stripped and/or star formation being enhanced at large radii. The peak of the Hα emission and that of the continuum are offset by less than 1 kpc. We investigate trends with the hot gas density as traced by the X-ray emission, and with the surface mass density as inferred from gravitational lens models and find no conclusive results. The ersity of morphologies and sizes observed in Hα illustrates the complexity of the environmental process that regulate star formation.
Publisher: Oxford University Press (OUP)
Date: 18-08-2020
Abstract: While there are many ways to identify substructures in galaxy clusters using different wavelengths, each technique has its own caveat. In this paper, we conduct a detailed substructure search and dynamical state characterization of Abell 2399, a galaxy cluster in the local Universe (z ∼ 0.0579), by performing a multiwavelength analysis and testing the results through hydrodynamical simulations. In particular, we apply a Gaussian mixture model to the spectroscopic data from SDSS, WINGS, and OmegaWINGS Surveys to identify substructures. We further use public XMM–Newton data to investigate the intracluster medium (ICM) thermal properties, creating temperature, metallicity, entropy, and pressure maps. Finally, we run hydrodynamical simulations to constrain the merger stage of this system. The ICM is very asymmetrical and has regions of temperature and pressure enhancement that evidence a recent merging process. The optical substructure analysis retrieves the two main X-ray concentrations. The temperature, entropy, and pressure are smaller in the secondary clump than in the main clump. On the other hand, its metallicity is considerably higher. This result can be explained by the scenario found by the hydrodynamical simulations where the secondary clump passed very near to the centre of the main cluster possibly causing the galaxies of that region to release more metals through the increase of ram-pressure stripping.
Publisher: American Astronomical Society
Date: 07-03-2019
Publisher: Oxford University Press (OUP)
Date: 31-08-2023
Publisher: American Astronomical Society
Date: 2022
Abstract: Ram pressure stripping has been proven to be effective in shaping galaxy properties in dense environments at low redshift. The availability of Multi Unit Spectroscopic Explorer (MUSE) observations of a s le of distant ( z ∼ 0.3–0.5) clusters has allowed one to search for galaxies subject to this phenomenon at significant lookback times. In this paper we describe how we discovered and characterized 13 ram-pressure-stripped galaxies in the central regions of two intermediate redshift ( z ∼ 0.3–0.4) clusters, A2744 and A370, using the MUSE spectrograph. Emission-line properties as well as stellar features have been analyzed to infer the presence of this gas-only stripping mechanism, that produces spectacular ionized gas tails (H α and even more astonishing [O ii ](3727, 3729)) departing from the main galaxy body. The inner regions of these two clusters reveal the predominance of such galaxies among blue star-forming cluster members, suggesting that ram pressure stripping was even more effective at intermediate redshift than in today’s universe. Interestingly, the resolved [O ii ]/H α line ratio in the stripped tails is exceptionally high compared to that in the disks of these galaxies, (which is comparable to that in normal low- z galaxies), suggesting lower gas densities and/or an interaction with the hot surrounding intracluster medium.
Publisher: American Astronomical Society
Date: 17-08-2020
Publisher: American Astronomical Society
Date: 05-2023
Abstract: We report the detection of a high density of redshift z ≈ 10 galaxies behind the foreground cluster A2744, selected from imaging data obtained recently with NIRCam on board JWST by three programs—GLASS-JWST, UNCOVER, and DDT#2756. To ensure robust estimates of the lensing magnification μ , we use an improved version of our model that exploits the first epoch of NIRCam images and newly obtained MUSE spectra and avoids regions with μ 5 where the uncertainty may be higher. We detect seven bright z ≈ 10 galaxies with demagnified rest frame −22 ≲ M UV ≲ −19 mag, over an area of ∼37 arcmin 2 . Taking into account photometric incompleteness and the effects of lensing on luminosity and cosmological volume, we find that the density of z ≈ 10 galaxies in the field is about 10× (3×) larger than the average at M UV ≈ −21 ( −20) mag reported so far. The density is even higher when considering only the GLASS-JWST data, which are the deepest and the least affected by magnification and incompleteness. The GLASS-JWST field contains five out of seven galaxies, distributed along an apparent filamentary structure of 2 Mpc in projected length, and includes a close pair of candidates with M UV −20 mag having a projected separation of only 16 kpc. These findings suggest the presence of a z ≈ 10 overdensity in the field. In addition to providing excellent targets for efficient spectroscopic follow-up observations, our study confirms the high density of bright galaxies observed in early JWST observations but calls for multiple surveys along independent lines of sight to achieve an unbiased estimate of their average density and a first estimate of their clustering.
Publisher: American Astronomical Society
Date: 14-01-2016
Publisher: American Astronomical Society
Date: 02-03-2015
Publisher: Oxford University Press (OUP)
Date: 10-07-2015
Publisher: American Astronomical Society
Date: 06-2021
Publisher: SPIE
Date: 30-08-2022
DOI: 10.1117/12.2627715
Publisher: Oxford University Press (OUP)
Date: 23-02-2018
DOI: 10.1093/MNRAS/STY500
Publisher: Oxford University Press (OUP)
Date: 10-06-2019
Publisher: American Astronomical Society
Date: 2023
Abstract: Star-forming galaxies can exhibit strong morphological differences between the rest-frame far-UV and optical, reflecting inhomogeneities in star formation and dust attenuation. We exploit deep, high-resolution, NIRCAM seven-band observations to take a first look at the morphology of galaxies in the epoch of reionization ( z 7), and its variation in the rest-frame wavelength range between Ly α and 6000–4000 Å, at z = 7–12. We find no dramatic variations in morphology with wavelength—of the kind that would have overturned anything we have learned from the Hubble Space Telescope. No significant trends between morphology and wavelengths are detected using standard quantitative morphology statistics. We detect signatures of mergers/interactions in 4/19 galaxies. Our results are consistent with a scenario in which Lyman-break galaxies—observed when the universe is only 400–800 Myr old—are growing via a combination of rapid, galaxy-scale star formation supplemented by the accretion of star-forming clumps and interactions.
Publisher: Oxford University Press (OUP)
Date: 21-05-2019
Publisher: American Astronomical Society
Date: 24-09-2014
Publisher: American Astronomical Society
Date: 05-02-2016
Publisher: American Astronomical Society
Date: 10-03-2017
Publisher: American Astronomical Society
Date: 14-10-2019
Publisher: EDP Sciences
Date: 10-2021
DOI: 10.1051/0004-6361/202141377
Abstract: Context. The morphology-density relation manifests the environmental dependence of the formation and evolution of galaxies as they continuously migrate through the cosmic web to ever denser environments. As gas-rich galaxies traverse the outskirts and inner regions of galaxy clusters, they experience sudden and radical changes in their gas content and star formation activity. Aims. The goal of this work is to gain an H I perspective on gas depletion mechanisms acting on galaxies and galaxy groups that are being accreted by a moderately massive galaxy cluster. We aim to study the relative importance and efficiency of processes such as ram-pressure stripping and tidal interactions as well as their dependency on the local and global environment of galaxies in the cluster core and in its surroundings. Methods. We have conducted a blind radio continuum and H I spectral line imaging survey with the MeerKAT radio telescope of a 2° × 2° area centred on the galaxy cluster Abell 2626. We have used the CARAcal pipeline to reduce the data, SoFiA to detect sources within the H I data cube, and GIPSY to construct spatially resolved information on the H I morphologies and kinematics of the H I detected galaxies. Results. We have detected H I in 219 galaxies with optical counterparts within the entire surveyed volume. We present the H I properties of each of the detected galaxies as a data catalogue and as an atlas page for each galaxy, including H I column-density maps, velocity fields, position-velocity diagrams, and global H I profiles. These data will also be used for case studies of identified ‘jellyfish’ galaxies and galaxy population studies by means of morphological classification of the direct H I detections as well as using the H I stacking technique.
Publisher: Oxford University Press (OUP)
Date: 30-09-2015
Publisher: American Astronomical Society
Date: 03-06-2013
Publisher: American Astronomical Society
Date: 16-09-2015
Publisher: Oxford University Press (OUP)
Date: 12-06-2023
Abstract: We present a search and characterization of ultra-diffuse galaxies (UDGs) in the Frontier Fields cluster Abell 2744 at $z$ = 0.308. We use JWST/NIRISS F200W observations, acquired as part of the GLASS-JWST Early Release Science programme, aiming to characterize morphologies of cluster UDGs and their diffuse stellar components. A total number of 22 UDGs are identified by our selection criteria using morphological parameters, down to stellar mass of ∼107 M⊙. The selected UDGs are systematically larger in effective radius in F200W than in Hubble Space Telescope (HST)/ACS F814W images, which implies that some of them would not have been identified as UDGs when selected at rest-frame optical wavelengths. In fact, we find that about one-third of the UDGs were not previously identified based on the F814W data. We observe a flat distribution of the UDGs in the stellar mass–size plane, similar to what is found for cluster quiescent galaxies at comparable mass. Our pilot study using the new JWST F200W filter showcases the efficiency of searching UDGs at cosmological distances, with 1/30 of the exposure time of the previous deep observing c aign with HST. Further studies with JWST focusing on spatially resolved properties of in idual sources will provide insight into their origin.
Publisher: EDP Sciences
Date: 21-11-2019
DOI: 10.1051/0004-6361/201936550
Abstract: Context. The upcoming new generation of optical spectrographs on four-meter-class telescopes, with their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage, will provide invaluable information for reconstructing the history of star formation in in idual galaxies up to redshifts of about 0.7. Aims. We aim at defining simple but robust and meaningful physical parameters that can be used to trace the coexistence of widely erse stellar components: younger stellar populations superimposed on the bulk of older ones. Methods. We produced spectra of galaxies closely mimicking data from the forthcoming Stellar Populations at intermediate redshifts Survey (StePS), a survey that uses the WEAVE spectrograph on the William Herschel Telescope. First, we assessed our ability to reliably measure both ultraviolet and optical spectral indices in galaxies of different spectral types for typically expected signal-to-noise ratios. We then analyzed such mock spectra with a Bayesian approach, deriving the probability density function of r - and u -band light-weighted ages as well as of their difference. Results. We find that the ultraviolet indices significantly narrow the uncertainties in estimating the r - and u -band light-weighted ages and their difference in in idual galaxies. These diagnostics, robustly retrievable for large galaxy s les even when observed at moderate signal-to-noise ratios, allow us to identify secondary episodes of star formation up to an age of ∼0.1 Gyr for stellar populations older than ∼1.5 Gyr, pushing up to an age of ∼1 Gyr for stellar populations older than ∼5 Gyr. Conclusions. The difference between r -band and u -band light-weighted ages is shown to be a powerful diagnostic to characterize and constrain extended star-formation histories and the presence of young stellar populations on top of older ones. This parameter can be used to explore the interplay between different galaxy star-formation histories and physical parameters such as galaxy mass, size, morphology, and environment.
Publisher: Oxford University Press (OUP)
Date: 19-03-2019
DOI: 10.1093/MNRAS/STZ809
Publisher: European Southern Observatory (ESO)
Date: 2017
Publisher: American Astronomical Society
Date: 11-2022
Abstract: We present a study of barred galaxies in the cluster environment, exploiting a s le of galaxies drawn from the extended WIde-field Nearby Galaxy-cluster Survey (OmegaWINGS) that covers up to the outer regions of 32 local X-ray selected clusters. Barred galaxies are identified through a semiautomatic analysis of ellipticity and position angle profiles. We find, in agreement with previous studies, a strong codependence of the bar fraction with the galaxy stellar mass and morphological type, being maximum for massive late-type galaxies. The fraction of barred galaxies decreases with increasing cluster mass and with decreasing clustercentric distance, a dependence that vanishes once we control for morphological type, which indicates that the likelihood of a galaxy hosting a bar in the cluster environment is determined by its morphological transformation. At large clustercentric distances, we detect a dependence on the distance to the nearest neighbor galaxy, suggesting that tidal forces with close companions are able to suppress the formation of bars or even destroy them. Barred galaxies in our s le are either early-type, star-forming galaxies located within the virial radii of the clusters or late-type quenched galaxies found beyond the virial radii of the clusters. We propose a scenario in which already quenched barred galaxies that fall into the clusters are centrally rejuvenated by the interplay of the perturbed gas by ram pressure and the bar, in galaxies that are undergoing a morphological transformation.
Publisher: American Astronomical Society
Date: 27-08-2010
Publisher: arXiv
Date: 2022
Publisher: American Astronomical Society
Date: 19-03-2018
Publisher: Oxford University Press (OUP)
Date: 19-03-2020
Abstract: We study the effects of the environment on galaxy quenching in the outskirts of clusters at 0.04 & z & 0.08. We use a subs le of 14 WINGS and OmegaWINGS clusters that are linked to other groups/clusters by filaments and study separately galaxies located in two regions in the outskirts of these clusters according to whether they are located towards the filaments’ directions or not. We also use s les of galaxies in clusters and field as a comparison. Filamentary structures linking galaxy groups/clusters were identified over the Six Degree Field Galaxy Redshift Survey Data Release 3. We find a fraction of passive galaxies in the outskirts of clusters intermediate between that of the clusters and the field’s. We find evidence of a more effective quenching in the direction of the filaments. We also analyse the abundance of post-starburst (PS) galaxies in the outskirts of clusters focusing our study on two extreme sets of galaxies according to their phase-space position: backsplash and true infallers. We find that up to $\\sim 70{{\\ \\rm per\\ cent}}$ of PS galaxies in the direction of filaments are likely backsplash, while this number drops to $\\sim 40{{\\ \\rm per\\ cent}}$ in the isotropic infall region. The presence of this small fraction of galaxies in filaments that are falling into clusters for the first time and have been recently quenched, supports a scenario in which a significant number of filament galaxies have been quenched long time ago.
Publisher: EDP Sciences
Date: 05-2019
DOI: 10.1051/0004-6361/201834970
Abstract: Exploiting a s le of galaxies drawn from the XXL-North multiwavelength survey, we present an analysis of the stellar population properties of galaxies at 0.1 ≤ z ≤ 0.5, by studying galaxy fractions and the star formation rate (SFR)–stellar mass ( M ⋆ ) relation. Furthermore, we exploit and compare two parametrisations of environment. When adopting a definition of “global” environment, we consider separately cluster virial ( r ≤ 1 r 200 ) and outer (1 r 200 r ≤ 3 r 200 ) members and field galaxies. We also distinguish between galaxies that belong or do not belong to superclusters, but never find systematic differences between the two subgroups. When considering the “local” environment, we take into account the projected number density of galaxies in a fixed aperture of 1 Mpc in the sky. We find that regardless of the environmental definition adopted, the fraction of blue or star-forming galaxies is the highest in the field or least dense regions and the lowest in the virial regions of clusters or highest densities. Furthermore, the fraction of star-forming galaxies is higher than the fraction of blue galaxies, regardless of the environment. This result is particularly evident in the virial cluster regions, most likely reflecting the different star formation histories of galaxies in different environments. Also the overall SFR– M ⋆ relation does not seem to depend on the parametrisation adopted. Nonetheless, the two definitions of environment lead to different results as far as the fraction of galaxies in transition between the star-forming main sequence and the quenched regime is concerned. In fact, using the local environment the fraction of galaxies below the main sequence is similar at low and high densities, whereas in clusters (and especially within the virial radii) a population with reduced SFR with respect to the field is observed. Our results show that the two parametrisations adopted to describe the environment have different physical meanings, i.e. are intrinsically related to different physical processes acting on galaxy populations and are able to probe different physical scales.
Publisher: EDP Sciences
Date: 2020
DOI: 10.1051/0004-6361/201833522
Abstract: We present a multi-wavelength analysis of the galaxies in nine clusters selected from the WINGS dataset, examining how galaxy structure varies as a function of wavelength and environment using the state of the art software GALAPAGOS-2 . We simultaneously fit single-Sérsic functions on three optical ( u , B and V ) and two near-infrared ( J and K ) bands thus creating a wavelength-dependent model of each galaxy. We measure the magnitudes, effective radius ( R e ), the Sérsic index ( n ), axis ratio, and position angle in each band. The s le contains 790 cluster members (located close to the cluster centre 0.64 × R 200 ) and 254 non-member galaxies that we further separate based on their morphology into ellipticals, lenticulars, and spirals. We find that the Sérsic index of all galaxies inside clusters remains nearly constant with wavelength while R e decreases as wavelength increases for all morphological types. We do not observe a significant variation on n and R e as a function of projected local density and distance from the clusters centre. Comparing the n and R e of bright cluster galaxies with a subs le of non-member galaxies we find that bright cluster galaxies are more concentrated (display high n values) and are more compact (low R e ). Moreover, the light profile (𝒩) and size (ℛ) of bright cluster galaxies does not change as a function of wavelength in the same manner as non-member galaxies.
Publisher: American Astronomical Society
Date: 17-12-2019
Publisher: Cambridge University Press (CUP)
Date: 03-2020
DOI: 10.1017/S1743921320002070
Abstract: Galaxies undergoing ram pressure stripping in clusters are an excellent opportunity to study the effects of environment on both the AGN and the star formation activity. We report here on the most recent results from the GASP survey. We discuss the AGN-ram pressure stripping connection and some evidence for AGN feedback in stripped galaxies. We then focus on the star formation activity, both in the disks and the tails of these galaxies, and conclude drawing a picture of the relation between multi-phase gas and star formation.
Publisher: American Astronomical Society
Date: 25-11-2021
Abstract: Diffuse ionized gas (DIG) is an important component of the interstellar medium that can provide insights into the different physical processes affecting the gas in galaxies. We utilize optical IFU observations of 71 gas-stripped and control galaxies from the Gas Stripping Phenomena in galaxies (GASP) survey, to analyze the gas properties of dense ionized gas and DIG, such as metallicity, ionization parameter log( q ), and the difference between the measured log[O i ]/H α and the value predicted by star-forming models given the measured log[O iii ]/H β (Δ log[O i ]/H α ). We compare these properties at different spatial scales, among galaxies at different gas-stripping stages, and between disks and tails of the stripped galaxies. The metallicity is similar between the dense gas and DIG at a given galactocentric radius. The log( q ) is lower for DIG compared to dense gas. The median values of log( q ) correlate best with stellar mass and the most massive galaxies show an increase in log( q ) toward their galactic centers. The DIG clearly shows higher Δ log[O i ]/H α values compared to the dense gas, with much of the spaxels having LIER/LINER-like emission. The DIG regions in the tails of highly stripped galaxies show the highest Δ log[O i ]/H α , exhibit high values of log( q ), and extend to large projected distances from star-forming areas (up to 10 kpc). We conclude that the DIG in the tails is at least partly ionized by a process other than star formation, probably by mixing, shocks, and accretion of inter-cluster and interstellar medium gas.
Publisher: Oxford University Press (OUP)
Date: 04-07-2019
Abstract: Exploiting the s le of 30 local star-forming, undisturbed late-type galaxies in different environments drawn from the GAs Stripping Phenomena in galaxies with MUSE (GASP), we investigate the spatially resolved star formation rate–mass ($\\rm \\Sigma _{SFR}$–$\\rm \\Sigma _\\ast$) relation. Our analysis includes also the galaxy outskirts (up to effective radii, re), a regime poorly explored by other Integral Field Spectrograph surveys. Our observational strategy allows us to detect H α out to more than 2.7re for 75 per cent of the s le. Considering all galaxies together, the correlation between the $\\rm \\Sigma _{SFR}$ and $\\rm \\Sigma _\\ast$ is quite broad, with a scatter of 0.3 dex. It gets steeper and shifts to higher $\\rm \\Sigma _\\ast$ values when external spaxels are excluded and moving from less to more massive galaxies. The broadness of the overall relation suggests galaxy-by-galaxy variations. Indeed, each object is characterized by a distinct $\\rm \\Sigma _{SFR}$ –$\\rm \\Sigma _\\ast$ relation and in some cases the correlation is very loose. The scatter of the relation mainly arises from the existence of bright off-centre star-forming knots whose $\\rm \\Sigma _{SFR}$–$\\rm \\Sigma _\\ast$ relation is systematically broader than that of the diffuse component. The $\\rm \\Sigma _{SFR}$–$\\rm \\Sigma _{tot \\, gas}$ (total gas surface density) relation is as broad as the $\\rm \\Sigma _{SFR}$–$\\rm \\Sigma _\\ast$ relation, indicating that the surface gas density is not a primary driver of the relation. Even though a large galaxy-by-galaxy variation exists, mean $\\rm \\Sigma _{SFR}$ and $\\rm \\Sigma _\\ast$ values vary of at most 0.7 dex across galaxies. We investigate the relationship between the local and global SFR–M* relation, finding that the latter is driven by the existence of the size–mass relation.
Location: South Africa
Start Date: 2016
End Date: 2015
Funder: University of Melbourne
View Funded ActivityStart Date: 2014
End Date: 2015
Funder: Japan Society for the Promotion of Science
View Funded ActivityStart Date: 2016
End Date: 03-2018
Amount: $314,436.00
Funder: Australian Research Council
View Funded Activity