ORCID Profile
0000-0001-5303-6830
Current Organisation
Federico Santa María Technical University
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Astronomical and Space Sciences | Cosmology and Extragalactic Astronomy
Publisher: EDP Sciences
Date: 11-02-2016
Publisher: American Astronomical Society
Date: 02-2021
Abstract: We study the stellar and gas kinematics of the brightest group galaxies (BGGs) in dynamically relaxed and unrelaxed galaxy groups for a s le of 154 galaxies in the SAMI galaxy survey. We characterize the dynamical state of the groups using the luminosity gap between the two most luminous galaxies and the BGG offset from the luminosity centroid of the group. We find that the misalignment between the rotation axis of gas and stellar components is more frequent in the BGGs in unrelaxed groups, although with quite low statistical significance. Meanwhile, galaxies whose stellar dynamics would be classified as “regular rotators” based on their kinemetry are more common in relaxed groups. We confirm that this dependency on group dynamical state remains valid at fixed stellar mass and Sérsic index. The observed trend could potentially originate from a differing BGG accretion history in virialized and evolving groups. Among the halo relaxation probes, the group BGG offset appears to play a stronger role than the luminosity gap on the stellar kinematic differences of the BGGs. However, both the group BGG offset and luminosity gap appear to roughly equally drive the misalignment between the gas and stellar component of the BGGs in one direction. This study offers the first evidence that the dynamical state of galaxy groups may influence the BGG's stellar and gas kinematics, and we call for further studies using a larger s le with higher signal-to-noise.
Publisher: American Astronomical Society
Date: 09-2023
Publisher: American Astronomical Society
Date: 15-10-2018
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: 26-12-2019
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: Oxford University Press (OUP)
Date: 06-12-2013
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: 30-07-2018
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: American Astronomical Society
Date: 20-10-2011
Publisher: Oxford University Press (OUP)
Date: 08-02-2023
Abstract: The distribution of galaxies and clusters of galaxies on the mega-parsec scale of the Universe follows an intricate pattern now famously known as the Large-Scale Structure or the Cosmic Web. To study the environments of this network, several techniques have been developed that are able to describe its properties and the properties of groups of galaxies as a function of their environment. In this work, we analyse the previously introduced framework: 1-Dimensional Recovery, Extraction, and Analysis of Manifolds (1-dream) on N-body cosmological simulation data of the Cosmic Web. The 1-DREAM toolbox consists of five Machine Learning methods, whose aim is the extraction and modelling of one-dimensional structures in astronomical big data settings. We show that 1-DREAM can be used to extract structures of different density ranges within the Cosmic Web and to create probabilistic models of them. For demonstration, we construct a probabilistic model of an extracted filament and move through the structure to measure properties such as local density and velocity. We also compare our toolbox with a collection of methodologies which trace the Cosmic Web. We show that 1-DREAM is able to split the network into its various environments with results comparable to the state-of-the-art methodologies. A detailed comparison is then made with the public code disperse, in which we find that 1-DREAM is robust against changes in s le size making it suitable for analysing sparse observational data, and finding faint and diffuse manifolds in low-density regions.
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: 10-11-2021
Publisher: Oxford University Press (OUP)
Date: 13-04-2012
Publisher: EDP Sciences
Date: 07-2023
DOI: 10.1051/0004-6361/202346599
Abstract: We analyse cold-gas distributions in Virgo cluster galaxies using resolved observations of CO(2-1), which traces molecular hydrogen (H 2 ), and H I from the Virgo Environment Traced In CO (VERTICO) and VLA Imaging of Virgo in Atomic Gas (VIVA) surveys. From a theoretical perspective, it is expected that environmental processes in clusters will have a stronger influence on diffuse atomic gas compared to the relatively dense molecular gas component, and that these environmental perturbations can compress the cold interstellar medium in cluster galaxies, leading to elevated star formation. In this work we observationally test these predictions for star-forming satellite galaxies within the Virgo cluster. We ided our Virgo galaxy s le into H I -normal, H I -tailed, and H I -truncated classes and show, unsurprisingly, that the H I -tailed galaxies have the largest quantitative H I asymmetries. We also compared Virgo galaxies to a control s le of non-cluster galaxies and find that the former, on average, have H I asymmetries that are 40 ± 10% larger than the latter. There is less separation between control, H I -normal, H I -tailed, and H I -truncated galaxies in terms of H 2 asymmetries, and on average, Virgo galaxies have H 2 asymmetries that are only marginally (20 ± 10%) larger than the control s le. We find a weak correlation between H I and H 2 asymmetries over our entire s le, but a stronger correlation for the galaxies that are strongly impacted by environmental perturbations. Finally, we ided the discs of the H I -tailed Virgo galaxies into a leading half and trailing half according to the observed tail direction. We find evidence for excess molecular gas mass on the leading halves of the disc. This excess molecular gas is accompanied by an excess in the star formation rate such that the depletion time is, on average, unchanged.
Publisher: Oxford University Press (OUP)
Date: 21-11-2018
Publisher: American Astronomical Society
Date: 16-03-2020
Publisher: Oxford University Press (OUP)
Date: 05-03-2015
DOI: 10.1093/MNRAS/STV228
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: Cambridge University Press (CUP)
Date: 2021
DOI: 10.1017/PASA.2021.18
Abstract: One of the key open questions in extragalactic astronomy is what stops star formation in galaxies. While it is clear that the cold gas reservoir, which fuels the formation of new stars, must be affected first, how this happens and what are the dominant physical mechanisms involved is still a matter of debate. At least for satellite galaxies, it is generally accepted that internal processes alone cannot be responsible for fully quenching their star formation, but that environment should play an important, if not dominant, role. In nearby clusters, we see ex les of cold gas being removed from the star-forming discs of galaxies moving through the intracluster medium, but whether active stripping is widespread and/or necessary to halt star formation in satellites, or quenching is just a consequence of the inability of these galaxies to replenish their cold gas reservoirs, remains unclear. In this work, we review the current status of environmental studies of cold gas in star-forming satellites in the local Universe from an observational perspective, focusing on the evidence for a physical link between cold gas stripping and quenching of the star formation. We find that stripping of cold gas is ubiquitous in satellite galaxies in both group and cluster environments. While hydrodynamical mechanisms such as ram pressure are important, the emerging picture across the full range of dark matter halos and stellar masses is a complex one, where different physical mechanisms may act simultaneously and cannot always be easily separated. Most importantly, we show that stripping does not always lead to full quenching, as only a fraction of the cold gas reservoir might be affected at the first pericentre passage. We argue that this is a key point to reconcile apparent tensions between statistical and detailed analyses of satellite galaxies, as well as disagreements between various estimates of quenching timescales. We conclude by highlighting several outstanding questions where we expect to see substantial progress in the coming decades, thanks to the advent of the Square Kilometre Array and its precursors, as well as the next-generation optical and millimeter facilities.
Publisher: Oxford University Press (OUP)
Date: 20-06-2016
Publisher: Oxford University Press (OUP)
Date: 13-10-2015
Publisher: Oxford University Press (OUP)
Date: 19-10-2022
Abstract: We conduct hydrodynamical cosmological zoom simulations of 14 voids to study the ability of haloes to accrete gas at different locations throughout the voids at z = 0. Measuring the relative velocity of haloes with respect to their ambient gas, we find that one-tenth of the haloes are expected to be unable to accrete external gas due to its fast flow passed them (so called ‘fast flow haloes’). These are typically located near void walls. We determine that these haloes have recently crossed the void wall and are still moving away from it. Their motion counter to that of ambient gas falling towards the void wall results in fast flows that make external gas accretion very challenging, and often cause partial gas loss via the resultant ram pressures. Using an analytical approach, we model the impact of such ram pressures on the gas inside haloes of different masses. A halo’s external gas accretion is typically cut off, with partial stripping of halo gas. For masses below a few times 109 M⊙, their halo gas is heavily truncated but not completely stripped. We identify numerous ex les of haloes with a clear jelly-fish like gas morphology, indicating their surrounding gas is being swept away, cutting them off from further external accretion. These results highlight how, even in the relatively low densities of void walls, a fraction of galaxies can interact with large-scale flows in a manner that has consequences for their gas content and ability to accrete gas.
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: 29-03-2017
Publisher: American Astronomical Society
Date: 2021
Abstract: We investigate the stellar populations of passive spiral galaxies as a function of mass and environment, using integral field spectroscopy data from the Sydney-AAO Multi-object Integral field spectrograph Galaxy Survey. Our s le consists of 52 cluster passive spirals and 18 group/field passive spirals, as well as a set of S0s used as a control s le. The age and [Z/H] estimated by measuring Lick absorption line strength indices both at the center and within 1 R e do not show a significant difference between the cluster and the field/group passive spirals. However, the field/group passive spirals with log( M ⋆ / M ⊙ ) ≳ 10.5 show decreasing [ α /Fe] along with stellar mass, which is ∼0.1 dex smaller than that of the cluster passive spirals. We also compare the stellar populations of passive spirals with S0s. In the clusters, we find that passive spirals show slightly younger age and lower [ α /Fe] than the S0s over the whole mass range. In the field/group, stellar populations show a similar trend between passive spirals and S0s. In particular, [ α /Fe] of the field/group S0s tend to be flattening with increasing mass above log( M ⋆ / M ⊙ ) ≳ 10.5, similar to the field/group passive spirals. We relate the age and [ α /Fe] of passive spirals to their mean infall time in phase space we find a positive correlation, in agreement with the prediction of numerical simulations. We discuss the environmental processes that can explain the observed trends. The results lead us to conclude that the formation of the passive spirals and their transformation into S0s may significantly depend on their environments.
Publisher: Oxford University Press (OUP)
Date: 14-01-2016
Publisher: American Astronomical Society
Date: 09-03-2016
Publisher: Oxford University Press (OUP)
Date: 19-09-2013
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: 10-2023
Publisher: American Astronomical Society
Date: 10-2023
Publisher: American Astronomical Society
Date: 13-07-2016
Publisher: Oxford University Press (OUP)
Date: 23-02-2018
DOI: 10.1093/MNRAS/STY500
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: Korea, Republic of
Start Date: 08-2021
End Date: 08-2024
Amount: $395,000.00
Funder: Australian Research Council
View Funded Activity