ORCID Profile
0000-0002-4985-3819
Current Organisation
University of Cambridge
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Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 10-05-2023
Abstract: We present an interstellar medium and stellar population analysis of three spectroscopically confirmed z & 7 galaxies in the Early Release Observations JWST/NIRCam and JWST/NIRSpec data of the SMACS J0723.3−7327 cluster. We use the Bayesian spectral energy distribution-fitting code prospector with a flexible star formation history (SFH), a variable dust attenuation law, and a self-consistent model of nebular emission (continuum and emission lines). Importantly, we self-consistently fit both the emission line fluxes from JWST/NIRSpec and the broad-band photometry from JWST/NIRCam, taking into account slit-loss effects. We find that these three z=7.6–8.5 galaxies (M⋆ ≈ 108 M⊙) are young with rising SFHs and mass-weighted ages of 3–4 Myr, though we find indications for underlying older stellar populations. The inferred gas-phase metallicities broadly agree with the direct metallicity estimates from the auroral lines. The galaxy with the lowest gas-phase metallicity (Zgas= 0.06 Z⊙) has a steeply rising SFH, is very compact (& .2 kpc), and has a high star formation rate surface density (ΣSFR ≈ 22 M⊙ yr−1 kpc−2), consistent with rapid gas accretion. The two other objects with higher gas-phase metallicities show more complex multicomponent morphologies on kpc scales, indicating that their recent increase in star formation rate is driven by mergers or internal, gravitational instabilities. We discuss effects of assuming different SFH priors or only fitting the photometric data. Our analysis highlights the strength and importance of combining JWST imaging and spectroscopy for fully assessing the nature of galaxies at the earliest epochs.
Publisher: EDP Sciences
Date: 05-2014
Publisher: American Association for the Advancement of Science (AAAS)
Date: 12-02-2021
Abstract: Galaxy formation in the early Universe is thought to have been a chaotic process, producing disturbed and asymmetric galaxy morphologies. Over billions of years, galaxies dynamically relaxed to form stable morphological features. Lelli et al. observed a distant galaxy at a redshift when the Universe was 1.2 billion years old (see the Perspective by Wardlow). They used gas and dust emission to measure its kinematics, and then modeled the mass distribution within the galaxy. The authors found that the galaxy contains a massive stellar bulge and a regularly rotating disk, features that models predict take billions of years to form. These results indicate that galaxy evolution is a more rapid process than previously thought. Science , this issue p. 713 see also p. 674
Publisher: American Astronomical Society
Date: 08-2023
Abstract: We present a s le of four emission-line galaxies at z = 6.11–6.35 that were serendipitously discovered using the commissioning data for the James Webb Space Telescope (JWST)/NIRCam wide-field slitless spectroscopy mode. One of them (at z = 6.11) has been reported previously, while the others are new discoveries. These sources are selected by the secure detections of both [O iii ] λ 5007 and H α lines with other fainter lines, which were tentatively detected in some cases (e.g., [O ii ] λ 3727, [O iii ] λ 4959). In the [O iii ]/H β –[N ii ]/H α Baldwin–Phillips–Terlevich diagram, these galaxies occupy the same parameter space as that of z ∼ 2 star-forming galaxies, indicating that they have been enriched rapidly to subsolar metallicities (∼0.4 Z ⊙ ), similar to galaxies with comparable stellar masses at much lower redshifts. The detection of strong H α lines suggests a higher ionizing photon production efficiency within galaxies in the early universe. We find brightening of the [O iii ] λ 5007 line-luminosity function (LF) from z = 3 to 6, and weak or no redshift evolution of the H α line LF from z = 2 to 6. Both LFs are underpredicted at z ∼ 6 by a factor of ∼10 in certain cosmological simulations. This further indicates a global Ly α photon escape fraction of 7%–10% at z ∼ 6, which is slightly lower than previous estimates through the comparison of the UV-derived star formation rate density and Ly α luminosity density. Our s le recovers 66 − 44 + 128 % of z = 6.0–6.6 galaxies in the survey volume with stellar masses greater than 5 × 10 8 M ⊙ , suggesting the ubiquity of strong H α and [O iii ] line emitters in the Epoch of Reionization, which will be further uncovered in the era of JWST.
Publisher: EDP Sciences
Date: 31-10-2013
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 17-02-2014
DOI: 10.1093/MNRAS/STU119
Publisher: Oxford University Press (OUP)
Date: 21-08-2023
Publisher: EDP Sciences
Date: 08-2011
Publisher: Oxford University Press (OUP)
Date: 25-10-2010
Publisher: EDP Sciences
Date: 23-12-2014
Publisher: American Astronomical Society
Date: 10-12-2014
Publisher: American Astronomical Society
Date: 29-06-2017
Publisher: American Astronomical Society
Date: 2023
Abstract: The dramatic first images with JWST demonstrated its power to provide unprecedented spatial detail for galaxies in the high-redshift universe. Here, we leverage the resolution and depth of the JWST Cosmic Evolution Early Release Science Survey data in the Extended Groth Strip to perform pixel-level morphological classifications of galaxies in JWST F150W imaging using the Morpheus deep-learning framework for astronomical image analysis. By cross-referencing with existing photometric redshift catalogs from the Hubble Space Telescope (HST) CANDELS survey, we show that JWST images indicate the emergence of disk morphologies before z ∼ 2 and with candidates appearing as early as z ∼ 5. By modeling the light profile of each object and accounting for the JWST point-spread function, we find the high-redshift disk candidates have exponential surface brightness profiles with an average Sérsic index 〈 n 〉 = 1.04 and % displaying “disky” profiles ( n 2). Comparing with prior Morpheus classifications in CANDELS we find that a plurality of JWST disk galaxy candidates were previously classified as compact based on the shallower HST imagery, indicating that the improved optical quality and depth of the JWST helps to reveal disk morphologies that were hiding in the noise. We discuss the implications of these early disk candidates on theories for cosmological disk galaxy formation.
Publisher: American Astronomical Society
Date: 03-2013
Publisher: Springer Science and Business Media LLC
Date: 06-2012
DOI: 10.1038/NATURE11073
Abstract: The Hubble Deep Field provides one of the deepest multiwavelength views of the distant Universe and has led to the detection of thousands of galaxies seen throughout cosmic time. An early map of the Hubble Deep Field at a wavelength of 850 micrometres, which is sensitive to dust emission powered by star formation, revealed the brightest source in the field, dubbed HDF 850.1 (ref. 2). For more than a decade, and despite significant efforts, no counterpart was found at shorter wavelengths, and it was not possible to determine its redshift, size or mass. Here we report a redshift of z = 5.183 for HDF 850.1, from a millimetre-wave molecular line scan. This places HDF 850.1 in a galaxy overdensity at z ≈ 5.2, corresponding to a cosmic age of only 1.1 billion years after the Big Bang. This redshift is significantly higher than earlier estimates and higher than those of most of the hundreds of submillimetre-bright galaxies identified so far. The source has a star-formation rate of 850 solar masses per year and is spatially resolved on scales of 5 kiloparsecs, with an implied dynamical mass of about 1.3 × 10(11) solar masses, a significant fraction of which is present in the form of molecular gas. Despite our accurate determination of redshift and position, a counterpart emitting starlight remains elusive.
Publisher: American Astronomical Society
Date: 02-2016
Publisher: EDP Sciences
Date: 28-07-2011
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 07-2010
Publisher: Springer Science and Business Media LLC
Date: 11-05-2022
DOI: 10.1038/S41586-022-04608-1
Abstract: Bright quasars, powered by accretion onto billion-solar-mass black holes, already existed at the epoch of reionization, when the Universe was 0.5-1 billion years old
Publisher: EDP Sciences
Date: 07-2010
Publisher: American Astronomical Society
Date: 03-2022
Abstract: We make use of Atacama Large Millimeter/submillimeter Array continuum observations of 15 luminous Lyman-break galaxies at z ∼ 7–8 to probe their dust-obscured star formation. These observations are sensitive enough to probe obscured star formation rates (SFRs) of 20 M ⊙ yr −1 (3 σ ). Six of the targeted galaxies show significant (≥3 σ ) dust-continuum detections, more than doubling the number of known dust-detected galaxies at z 6.5. Their IR luminosities range from 2.7 × 10 11 L ⊙ to 1.1 × 10 12 L ⊙ , equivalent to obscured SFRs of 25 to 101 M ⊙ yr −1 . We use our results to quantify the correlation of the infrared excess (IRX) on the UV-continuum slope β UV and stellar mass. Our results are most consistent with a Small Magellanic Cloud (SMC) attenuation curve for intrinsic UV-slopes β UV , intr of −2.63 and most consistent with an attenuation curve in between SMC and Calzetti for β UV , intr slopes of −2.23, assuming a dust temperature T d of 50 K. Our fiducial IRX–stellar mass results at z ∼ 7–8 are consistent with marginal evolution from z ∼ 0. We then show how both results depend on T d . For our six dust-detected sources, we estimate their dust masses and find that they are consistent with dust production from supernovae if the dust destruction is low ( %). Finally we determine the contribution of dust-obscured star formation to the SFR density for UV luminous ( H −21.5 mag: ≳1.7 L * UV ) z ∼ 7–8 galaxies, finding that the total SFR density at z ∼ 7 and z ∼ 8 from bright galaxies is 0.20 − 0.10 + 0.10 dex and 0.23 − 0.09 + 0.06 dex higher, respectively i.e., ∼ 1 3 of the star formation in ≳1.7 L * UV galaxies at z ∼ 7–8 is obscured by dust.
Publisher: American Astronomical Society
Date: 07-2023
Abstract: We present JWST NIRCam nine-band near-infrared imaging of the luminous z = 10.6 galaxy GN-z11 from the JWST Advanced Deep Extragalactic Survey of the GOODS-N field. We find a spectral energy distribution (SED) entirely consistent with the expected form of a high-redshift galaxy: a clear blue continuum from 1.5 to 4 μ m with a complete dropout in F115W. The core of GN-z11 is extremely compact in JWST imaging. We analyze the image with a two-component model, using a point source and a Sérsic profile that fits to a half-light radius of 200 pc and an index n = 0.9. We find a low-surface-brightness haze about 0.″4 to the northeast of the galaxy, which is most likely a foreground object but might be a more extended component of GN-z11. At a spectroscopic redshift of 10.60 (Bunker et al. 2023), the comparison of the NIRCam F410M and F444W images spans the Balmer jump. From population-synthesis modeling, here assuming no light from an active galactic nucleus, we reproduce the SED of GN-z11, finding a stellar mass of ∼10 9 M ⊙ , a star formation rate of ∼20 M ⊙ yr −1 , and a young stellar age of ∼20 Myr. Since massive galaxies at high redshift are likely to be highly clustered, we search for faint neighbors of GN-z11, finding nine galaxies out to ∼5 comoving Mpc transverse with photometric redshifts consistent with z = 10.6, and a tenth more tentative dropout only 3″ away. This is consistent with GN-z11 being hosted by a massive dark-matter halo (≈8 × 10 10 M ⊙ ), though lower halo masses cannot be ruled out.
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 12-2009
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 12-2010
Publisher: Oxford University Press (OUP)
Date: 21-08-2023
Publisher: EDP Sciences
Date: 09-2012
Publisher: American Astronomical Society
Date: 30-01-2014
Publisher: American Astronomical Society
Date: 30-01-2014
Publisher: EDP Sciences
Date: 07-2010
Publisher: American Astronomical Society
Date: 27-10-2023
Publisher: Research Square Platform LLC
Date: 04-02-2022
DOI: 10.21203/RS.3.RS-634683/V2
Abstract: Black hole feedback has been widely implemented as the key recipe to quench star formation inmassive galaxies in modern semi-analytic models and hydrodynamical simulations. As the theoreticaldetails surrounding the accretion and feedback of black holes continue to be refined, various feedbackmodels have been implemented across simulations, with notable differences in their outcomes. Yet,most of these simulations have successfully reproduced some observations, such as stellar mass functionand star formation rate density in the local Universe. We use the recent observation on the change ofneutral hydrogen gas mass (including both H2 and Hi) with star formation rate of massive central discgalaxies as a critical constraint of black hole feedback models across several simulations. We nd thatthe predictions of IllustrisTNG agree with the observations much better than the other models testedin this work. This favors IllustrisTNG's treatment of active galactic nuclei - where kinetic winds aredriven by black holes at low accretion rates - as more plausible amongst those we test. In turn, thisalso indirectly supports the idea that the massive central disc galaxy population in the local Universewas likely quenched by AGN feedback.
Publisher: Research Square Platform LLC
Date: 02-07-2021
DOI: 10.21203/RS.3.RS-634683/V1
Abstract: Black hole feedback has been widely implemented as the key recipe to quench star formation in massive galaxies in modern semi-analytic models and hydrodynamical simulations. As the theoretical details surrounding the accretion and feedback of black holes continue to be refined, various feedback models have been implemented across simulations, with notable differences in their outcomes. Yet, most of these simulations have successfully reproduced some observations, such as stellar mass function and star formation rate density in the local Universe. We use the recent observation on the change of neutral hydrogen gas mass (including both H2 and H1) with star formation rate of massive central disc galaxies as a critical test of black hole feedback models across several simulations. We find that IllustrisTNG reproduces the observations significantly better than the other models that we have tested. This favors IllustrisTNG's treatment of active galactic nuclei---where kinetic winds are driven by black holes at low accretion rates---as the most physically plausible amongst those we test. In turn, this also supports the idea that the massive central disc galaxy population in the local Universe was likely quenched by AGN feedback.
Publisher: EDP Sciences
Date: 04-2012
Publisher: American Astronomical Society
Date: 17-08-2010
Publisher: American Astronomical Society
Date: 11-02-2013
Publisher: IOP Publishing
Date: 03-2023
Abstract: The Near-Infrared Spectrograph (NIRSpec) is one of the four focal plane instruments on the James Webb Space Telescope. In this paper, we summarize the in-orbit performance of NIRSpec, as derived from data collected during its commissioning c aign and the first few months of nominal science operations. More specifically, we discuss the performance of some critical hardware components such as the two NIRSpec Hawaii-2RG detectors, wheel mechanisms, and the microshutter array. We also summarize the accuracy of the two target acquisition procedures used to accurately place science targets into the slit apertures, discuss the current status of the spectrophotometric and wavelength calibration of NIRSpec spectra, and provide the “as measured” sensitivity in all NIRSpec science modes. Finally, we point out a few important considerations for the preparation of NIRSpec science programs.
Publisher: American Astronomical Society
Date: 20-08-2010
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Roberto Maiolino.