ORCID Profile
0000-0002-2057-5376
Current Organisation
Swinburne University of Technology
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Publisher: American Astronomical Society
Date: 14-10-2009
Publisher: American Astronomical Society
Date: 02-2023
Abstract: The advent of the James Webb Space Telescope (JWST) signals a new era in exploring galaxies in the high- z universe. Current and upcoming JWST imaging will potentially detect galaxies at z ∼ 20, creating a new urgency in the quest to infer accurate photometric redshifts (photo- z ) for in idual galaxies from their spectral energy distributions, as well as masses, ages, and star formation rates. Here we illustrate the utility of informed priors encoding previous observations of galaxies across cosmic time in achieving these goals. We construct three joint priors encoding empirical constraints of redshifts, masses, and star formation histories in the galaxy population within the Prospector Bayesian inference framework. In contrast with uniform priors, our model breaks an age–mass–redshift degeneracy, and thus reduces the mean bias error in masses from 0.3 to 0.1 dex, and in ages from 0.6 to 0.2 dex in tests done on mock JWST observations. Notably, our model recovers redshifts at least as accurately as the state-of-the-art photo- z code EAzY in deep JWST fields, but with two advantages: tailoring a model based on a particular survey is rendered mostly unnecessary given well-motivated priors obtaining joint posteriors describing stellar, active galactic nuclei, gas, and dust contributions becomes possible. We can now confidently use the joint distribution to propagate full non-Gaussian redshift uncertainties into inferred properties of the galaxy population. This model, “ Prospector - β ,” is intended for fitting galaxy photometry where the redshift is unknown, and will be instrumental in ensuring the maximum science return from forthcoming photometric surveys with JWST. The code is made publicly available online as a part of Prospector 9 9 The version used in this work corresponds to the state of the Git repository at commit d-j rospector/commit/820ad72363a1f9c22cf03610bfe6e361213385cd . .
Publisher: Oxford University Press (OUP)
Date: 21-02-2022
Abstract: We analyse FIR dust continuum measurements for 14 galaxies (redshift z ≈ 7) in the ALMA Reionization Era Bright Emission Line Survey (REBELS) Large Program to derive their physical properties. Our model uses three input data, i.e. (a) the UV spectral slope, β, (b) the observed UV continuum flux at 1500 Å, F1500, (c) the observed continuum flux at $\\approx 158\\, \\mu$m, F158, and considers Milky Way (MW) and SMC extinction curves, along with different dust geometries. We find that REBELS galaxies have 28−90.5 per cent of their star formation obscured the total (UV+IR) star formation rates are in the range $31.5 \\lt {\\rm SFR}/({\\rm M}_\\odot \\, {\\rm yr}^{-1}) \\lt 129.5$. The s le-averaged dust mass and temperature are $(1.3\\pm 1.1)\\times 10^7 \\, \\mathrm{M}_\\odot$ and 52 ± 11 K, respectively. However, in some galaxies dust is particularly abundant (REBELS-14, $M^{\\prime }_{\\rm d} \\approx 3.4 \\times 10^7 \\, \\mathrm{M}_\\odot$), or hot (REBELS-18, $T^{\\prime }_{\\rm d} \\approx 67$ K). The dust distribution is compact (& .3 kpc for 70 per cent of the galaxies). The inferred dust yield per supernova is $0.1 \\le y_{\\rm d}/\\, \\mathrm{M}_\\odot \\le 3.3$, with 70 per cent of the galaxies requiring $y_{\\rm d} \\lt 0.25 \\, \\mathrm{M}_\\odot$. Three galaxies (REBELS-12, 14, 39) require $y_{\\rm d} \\gt 1 \\, \\mathrm{M}_\\odot$, which is likely inconsistent with pure SN production, and might require dust growth via accretion of heavy elements from the interstellar medium. With the SFR predicted by the model and a MW extinction curve, REBELS galaxies detected in [C ii] nicely follow the local LCII−SFR relation, and are approximately located on the Kennicutt–Schmidt relation. The s le-averaged gas depletion time is $0.11\\, y_{\\rm P}^{-2}$ Gyr, where yP is the ratio of the gas-to-stellar distribution radius. For some systems, a solution simultaneously matching the observed (β, F1500, F158) values cannot be found. This occurs when the index Im = (F158/F1500)/(β − βint), where βint is the intrinsic UV slope, exceeds $I_m^{*}\\approx 1120$ for an MW curve. For these objects, we argue that the FIR and UV emitting regions are not co-spatial, questioning the use of the IRX–β relation.
Publisher: American Astronomical Society
Date: 25-08-2016
Publisher: Springer Science and Business Media LLC
Date: 04-2017
DOI: 10.1038/NATURE21680
Abstract: Finding massive galaxies that stopped forming stars in the early Universe presents an observational challenge because their rest-frame ultraviolet emission is negligible and they can only be reliably identified by extremely deep near-infrared surveys. These surveys have revealed the presence of massive, quiescent early-type galaxies appearing as early as redshift z ≈ 2, an epoch three billion years after the Big Bang. Their age and formation processes have now been explained by an improved generation of galaxy-formation models, in which they form rapidly at z ≈ 3-4, consistent with the typical masses and ages derived from their observations. Deeper surveys have reported evidence for populations of massive, quiescent galaxies at even higher redshifts and earlier times, using coarsely s led photometry. However, these early, massive, quiescent galaxies are not predicted by the latest generation of theoretical models. Here we report the spectroscopic confirmation of one such galaxy at redshift z = 3.717, with a stellar mass of 1.7 × 10
Publisher: American Astronomical Society
Date: 03-04-2017
Publisher: American Astronomical Society
Date: 13-07-2018
Publisher: American Astronomical Society
Date: 24-03-2017
Publisher: American Astronomical Society
Date: 02-04-2015
Publisher: Cambridge University Press (CUP)
Date: 08-2009
DOI: 10.1017/S174392131000270X
Abstract: How did galaxies evolve from primordial fluctuations to the well-ordered but erse population of disk and elliptical galaxies that we observe today? Stellar populations synthesis models have become a crucial tool in addressing this question by helping us to interpret the spectral energy distributions of present-day galaxies and their high redshift progenitors in terms of fundamental characteristics such as stellar mass and age. I will review our current knowledge on the evolution of stellar populations in early- and late type galaxies at z 1 and the tantalizing – but incomplete – view of the stellar populations in galaxies at 1 z 3, during the global peak of star formation. Despite great progress, many fundamental questions remain: what processes trigger episodes of galaxy-scale star formation and what quenches them? To what degree does the star formation history of galaxies depend on the merger history, (halo) mass, or local environment? I will discuss some of the challenges posed in interpreting current data and what improved results might be expected from new observational facilities in the near- and more distant future.
Publisher: American Astronomical Society
Date: 14-07-2015
Publisher: American Astronomical Society
Date: 08-2022
Abstract: We measure, for the first time, the median equivalent width (EW) of H α +[N ii ] in star-forming galaxies at z ∼ 8. Our estimate leverages the unique photometric depth of the Spitzer/IRAC 5.8 μ m band mosaics (probing ≈5500–7100 Å at z ∼ 8) of the GOODS Reionization Era Wide Area Treasury from Spitzer (GREATS) program. We median-stacked the st s of 102 Lyman-break galaxies in the 3.6, 4.5, 5.8, and 8.0 μ m bands, after carefully removing potential contamination from neighboring sources. We infer an extreme rest-frame EW 0 (H α +[N ii ]) = 2328 − 1127 + 1326 Å from the measured red [3.6] − [5.8] = 0.82 ± 0.27 mag, consistent with young (≲10 7 yr) average stellar population ages at z ∼ 8. This implies an ionizing photon production efficiency of l o g ( ξ i o n , 0 / e r g H z − 1 ) = 25.97 − 0.28 + 0.18 . Such a high value for photoproduction, similar to the highest values found at z ≲ 4, indicates that only modest escape fractions f esc ≲ 0.3 (at 2 σ ) are sufficient for galaxies brighter than M UV −18 mag to reionize the neutral hydrogen at z ∼ 8. This requirement is relaxed even more to f esc ≤ 0.1 when considering galaxies brighter than M UV ≈ −13 mag, consistent with recent luminosity functions and as typically assumed in studies addressing reionization. These exceptional results clearly indicate that galaxies can be the dominant source of reionizing photons, and provide us with an exciting glimpse into what we might soon learn about the early universe, and particularly about the reionization epoch, from forthcoming JWST/MIRI and NIRCam programs.
Publisher: Oxford University Press (OUP)
Date: 14-03-2017
DOI: 10.1093/MNRAS/STX605
Publisher: American Astronomical Society
Date: 04-11-2016
Publisher: American Astronomical Society
Date: 09-2023
Publisher: American Astronomical Society
Date: 02-2023
Abstract: We present a new rest-frame color–color selection method using synthetic u s − g s and g s − i s , ( ugi ) s colors to identify star-forming and quiescent galaxies. Our method is similar to the widely used U − V versus V − J ( UVJ ) diagram. However, UVJ suffers known systematics. Spectroscopic c aigns have shown that UVJ -selected quiescent s les at z ≳ 3 include ∼10%–30% contamination from galaxies with dust-obscured star formation and strong emission lines. Moreover, at z 3, UVJ colors are extrapolated because the rest-frame band shifts beyond the coverage of the deepest bandpasses at μ m (typically Spitzer/IRAC 4.5 μ m or future JWST/NIRCam observations). We demonstrate that ( ugi ) s offers improvements to UVJ at z 3, and can be applied to galaxies in the JWST era. We apply ( ugi ) s selection to galaxies at 0.5 z 6 from the (observed) 3D-HST and UltraVISTA catalogs, and to the (simulated) JAGUAR catalogs. We show that extrapolation can affect ( V − J ) 0 color by up to 1 mag, but changes ( g s − i s ) 0 color by ≤0.2 mag, even at z ≃ 6. While ( ugi ) s -selected quiescent s les are comparable to UVJ in completeness (both achieve ∼85%–90% at z = 3–3.5), ( ugi ) s reduces contamination in quiescent s les by nearly a factor of 2, from ≃35% to ≃17% at z = 3, and from ≃60% to ≃33% at z = 6. This leads to improvements in the true-to-false-positive ratio (TP/FP), where we find TP/FP ≳2.2 for ( ugi ) s at z ≃ 3.5 − 6, compared to TP/FP 1 for UVJ -selected s les. This indicates that contaminants will outnumber true quiescent galaxies in UVJ at these redshifts, while ( ugi ) s will provide higher-fidelity s les.
Publisher: American Astronomical Society
Date: 25-07-2023
Abstract: Recent JWST/NIRCam imaging taken for the ultra-deep UNCOVER program reveals a very red dropout object at z phot ≃ 7.6, triply imaged by the galaxy cluster A2744 ( z d = 0.308). All three images are very compact, i.e., unresolved, with a delensed size upper limit of r e ≲ 35 pc. The images have apparent magnitudes of m F444W ∼ 25−26 AB, and the magnification-corrected absolute UV magnitude of the source is M UV,1450 = −16.81 ± 0.09. From the sum of observed fluxes and from a spectral energy distribution (SED) analysis, we obtain estimates of the bolometric luminosities of the source of L bol ≳ 10 43 erg s −1 and L bol ∼ 10 44 –10 46 erg s −1 , respectively. Based on its compact, point-like appearance, its position in color–color space, and the SED analysis, we tentatively conclude that this object is a UV-faint dust-obscured quasar-like object, i.e., an active galactic nucleus at high redshift. We also discuss other alternative origins for the object’s emission features, including a massive star cluster, Population III, supermassive, or dark stars, or a direct-collapse black hole. Although populations of red galaxies at similar photometric redshifts have been detected with JWST, this object is unique in that its high-redshift nature is corroborated geometrically by lensing, that it is unresolved despite being magnified—and thus intrinsically even more compact—and that it occupies notably distinct regions in both size–luminosity and color–color space. Planned UNCOVER JWST/NIRSpec observations, scheduled in Cycle 1, will enable a more detailed analysis of this object.
Publisher: American Astronomical Society
Date: 30-09-2019
Publisher: American Astronomical Society
Date: 09-04-2020
Publisher: American Astronomical Society
Date: 11-10-2016
Publisher: Apollo - University of Cambridge Repository
Date: 2022
DOI: 10.17863/CAM.82825
Publisher: American Astronomical Society
Date: 05-02-2020
Publisher: American Astronomical Society
Date: 20-03-2017
Publisher: Apollo - University of Cambridge Repository
Date: 2022
DOI: 10.17863/CAM.90800
Publisher: American Astronomical Society
Date: 06-2016
Publisher: American Astronomical Society
Date: 03-05-2018
Publisher: American Astronomical Society
Date: 18-07-2016
Publisher: American Astronomical Society
Date: 23-06-2023
Abstract: We present new Spitzer Infrared Array Camera (IRAC) 3.6 and 4.5 μ m mosaics of three fields, E-COSMOS, DEEP2-F3, and ELAIS-N1. Our mosaics include both new IRAC observations as well as reprocessed archival data in these fields. These fields are part of the HSC-Deep grizy survey and have a wealth of additional ancillary data. The addition of these new IRAC mosaics is critical in allowing for improved photometric redshifts and stellar population parameters at cosmic noon and earlier epochs. The total area mapped by this work is ∼17 deg 2 with a mean integration time of ≈1200s, providing a median 5 σ depth of 23.7(23.3) at 3.6(4.5) μ m in AB. We perform SExtractor photometry both on the combined mosaics as well as the single-epoch mosaics taken ≈6 months apart. The resultant IRAC number counts show good agreement with previous studies. In combination with the wealth of existing and upcoming spectrophotometric data in these fields, our IRAC mosaics will enable a wide range of galactic evolution and AGN studies. With that goal in mind, we make the combined IRAC mosaics and coverage maps of these three fields publicly available.
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.CHOM.2016.02.006
Abstract: The obligate intracellular lifestyle of apicomplexan parasites necessitates an invasive phase underpinned by timely and spatially controlled secretion of apical organelles termed micronemes. In Toxoplasma gondii, extracellular potassium levels and other stimuli trigger a signaling cascade culminating in phosphoinositide-phospholipase C (PLC) activation, which generates the second messengers diacylglycerol (DAG) and IP3 and ultimately results in microneme secretion. Here we show that a delicate balance between DAG and its downstream product, phosphatidic acid (PA), is essential for controlling microneme release. Governing this balance is the apicomplexan-specific DAG-kinase-1, which interconverts PA and DAG, and whose depletion impairs egress and causes parasite death. Additionally, we identify an acylated pleckstrin-homology (PH) domain-containing protein (APH) on the microneme surface that senses PA during microneme secretion and is necessary for microneme exocytosis. As APH is conserved in Apicomplexa, these findings highlight a potentially widely used mechanism in which key lipid mediators regulate microneme exocytosis.
Publisher: American Astronomical Society
Date: 11-08-2016
Publisher: American Astronomical Society
Date: 28-09-2022
Abstract: Galaxy sizes and their evolution over cosmic time have been studied for decades and serve as key tests of galaxy formation models. However, at z ≳ 1 these studies have been limited by a lack of deep, high-resolution rest-frame infrared imaging that accurately traces stellar mass distributions. Here, we leverage the new capabilities of the James Webb Space Telescope (JWST) to measure the 4.4 μ m sizes of ∼1000 galaxies with log M * / M ⊙ ≥ 9 and 1.0 ≤ z ≤ 2.5 from public CEERS imaging in the Extended Groth Strip deep field. We compare the sizes of galaxies measured from NIRCam imaging at 4.4 μ m ( λ rest ∼ 1.6 μ m) with sizes measured at 1.5 μ m ( λ rest ∼ 5500 Å). We find that, on average, galaxy half-light radii are ∼9% smaller at 4.4 μ m than 1.5 μ m in this s le. This size difference is markedly stronger at higher stellar masses and redder rest-frame V − J colors: galaxies with M * ∼ 10 11 M ⊙ have 4.4 μ m sizes that are ∼30% smaller than their 1.5 μ m sizes. Our results indicate that galaxy mass profiles are significantly more compact than their rest-frame optical light profiles at cosmic noon, and demonstrate that spatial variations in age and attenuation are important, particularly for massive galaxies. The trend we find here impacts our understanding of the size growth and evolution of galaxies, and suggests that previous studies based on rest-frame optical light may not have captured the mass-weighted structural evolution of galaxies. This paper represents a first step toward a new understanding of the morphologies of early massive galaxies enabled by JWST’s infrared window into the distant universe.
Publisher: American Astronomical Society
Date: 12-2021
Abstract: We present the deepest Spitzer/InfraRed Array Camera (IRAC) 3.6, 4.5, 5.8, and 8.0 μ m wide-area mosaics yet over the Great Observatories Origins Deep Survey (GOODS)-N and GOODS-S fields as part of the GOODS Reionization Era wide-Area Treasury from Spitzer (GREATS) project. We reduced and mosaicked in a self-consistent way observations taken by the 11 different Spitzer/IRAC programs over the two GOODS fields from 12 yr of Spitzer cryogenic and warm-mission data. The cumulative depth in the 3.6 μ m and 4.5 μ m bands amounts to ∼4260 hr, ∼1220 hr of which are new very deep observations from the GREATS program itself. In the deepest area, the full-depth mosaics reach ≳200 hr over an area of ∼100 arcmin 2 , corresponding to a sensitivity of ∼29 AB magnitude at 3.6 μ m (1 σ for point sources). Archival cryogenic 5.8 μ m and 8.0 μ m band data (a cumulative 976 hr) are also included in the release. The mosaics are projected onto the tangential plane of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey/GOODS at a 0.″3 pixel −1 scale. This paper describes the methodology enabling, and the characteristics of, the public release of the mosaic science images, the corresponding coverage maps in the four IRAC bands, and the empirical point-spread functions (PSFs). These PSFs enable mitigation of the source blending effects by taking into account the complex position-dependent variation in the IRAC images. The GREATS data products are in the Infrared Science Archive. We also release the deblended 3.6–8.0 μ m photometry 9192 Lyman-break galaxies at z ∼ 3.5–10. GREATS will be the deepest mid-infrared imaging until the James Webb Space Telescope and, as such, constitutes a major resource for characterizing early galaxy assembly.
Publisher: American Astronomical Society
Date: 05-02-2020
Publisher: American Astronomical Society
Date: 05-2023
Abstract: With just a month of data, JWST is already transforming our view of the universe, revealing and resolving starlight in unprecedented populations of galaxies. Although “HST-dark” galaxies have previously been detected at long wavelengths, these observations generally suffer from a lack of spatial resolution, which limits our ability to characterize their sizes and morphologies. Here we report on a first view of starlight from a subset of the HST-dark population that is bright with JWST/NIRCam (4.4 μ m 24.5 mag) and very faint or even invisible with HST ( .6 μ m). In this Letter we focus on a dramatic and unanticipated population of physically extended galaxies (≳0.″25). These 12 galaxies have photometric redshifts 2 z 6, high stellar masses M ⋆ ≳ 10 10 M ⊙ , and significant dust-attenuated star formation. Surprisingly, the galaxies have elongated projected axis ratios at 4.4 μ m, suggesting that the population is disk dominated or prolate and we hence refer to them as ultrared flattened objects. Most of the galaxies appear red at all radii, suggesting significant dust attenuation throughout. With R e (F444W) ∼ 1–2 kpc, the galaxies are similar in size to compact massive galaxies at z ∼ 2 and the cores of massive galaxies and S0s at z ∼ 0. The stellar masses, sizes, and morphologies of the s le suggest that some could be progenitors of lenticular or fast-rotating galaxies in the local universe. The existence of this population suggests that our previous censuses of the universe may have missed massive, dusty edge-on disks, in addition to dust-obscured starbursts.
Publisher: American Astronomical Society
Date: 22-03-2016
Publisher: American Astronomical Society
Date: 21-09-2017
Publisher: American Astronomical Society
Date: 21-07-2020
Publisher: American Astronomical Society
Date: 03-11-2018
Abstract: Deep near-infrared photometric surveys are efficient in identifying high-redshift galaxies, however, they can be prone to systematic errors in photometric redshift. This is particularly salient when there is limited s ling of key spectral features of a galaxy’s spectral energy distribution (SED), such as for quiescent galaxies where the expected age-sensitive Balmer/4000 Å break enters the K -band at z 4. With single-filter s ling of this spectral feature, degeneracies between SED models and redshift emerge. A potential solution to this comes from splitting the K band into multiple filters. We use simulations to show an optimal solution is to add two medium-band filters, K blue ( λ cen = 2.06 μ m, Δ λ = 0.25 μ m) and K red ( λ cen = 2.31 μ m, Δ λ = 0.27 μ m), that are complementary to the existing K s filter. We test the impact of the K -band filters with simulated catalogs comprised of galaxies with varying ages and signal-to-noise. The results suggest that the K -band filters do improve photometric redshift constraints on z 4 quiescent galaxies, increasing precision and reducing outliers by up to 90%. We find that the impact from the K -band filters depends on the signal-to-noise, the redshift, and the SED of the galaxy. The filters we designed were built and used to conduct a pilot of the FLAMINGOS-2 Extragalactic Near-Infrared K -band Split survey. While no new z 4 quiescent galaxies are identified in the limited area pilot, the K blue and K red filters indicate strong Balmer/4000 Å breaks in existing candidates. Additionally, we identify galaxies with strong nebular emission lines, for which the K -band filters increase photometric redshift precision and in some cases indicate extreme star formation.
Publisher: American Astronomical Society
Date: 25-08-2023
Abstract: The [C ii ] 158 μ m line has long been proposed as a promising line to spectroscopically confirm galaxies in the epoch of reionization. In this paper, we present the results of new ALMA observations spectral scanning for [C ii ] in six particularly luminous Lyman-break galaxies at z ∼ 7. The six sources were drawn from a s le of bright z ∼ 7 galaxies identified using the wide-area optical, near-IR, and Spitzer/IRAC data over the COSMOS/UltraVISTA field and were targeted on the basis of tight constraints on their redshifts from their IRAC [3.6]–[4.5] colors. We detect significant ( σ ) [C ii ] lines in three of our six targets (50%) cospatial with the rest-UV emission from the ground/space-based near-IR imaging. The luminosities of the [C ii ] lines lie in the range 5.6–8.8 × 10 8 L ⊙ , consistent with the local [C ii ]–SFR relation. Meanwhile, their [C ii ]/ L IR ∼ 1–3 × 10 −3 ratios are slightly elevated compared to local ( U )LIRGS. This could be due to lower dust-to-gas or dust-to-metal ratios. We also find that our sources display a large kinematic ersity, with one source showing signs of rotation, one source a likely major merger, and one dispersion-dominated source that might contain a bright star-forming clump. Our results highlight the effectiveness of spectral scans with ALMA in spectroscopically confirming luminous galaxies in the epoch of reionization, something that is being be applied on a significantly larger s le in the ongoing REBELS large program.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2023
Publisher: American Astronomical Society
Date: 28-06-2017
Publisher: American Astronomical Society
Date: 27-01-2023
Abstract: We present the deepest constraints yet on the median rest-UV+optical spectral energy distribution (SED) of z ∼ 10 galaxies prior to James Webb Space Telescope science operations. We constructed stacks based on four robust J 125 dropouts, previously identified across the GOODS fields. We used archival Hubble Space Telescope/Wide Field Camera 3 data and the full-depth Spitzer/IRAC mosaics from the GREATS program, the deepest coverage at ∼3–5 μ m to date. The most remarkable feature of the SED is a blue IRAC [3.6]–[4.5] = −0.18 ± 0.25 mag color. We also find a nearly flat H 160 − [3.6] = 0.07 ± 0.22 mag color, corresponding to a UV slope β = −1.92 ± 0.25. This is consistent with previous studies and indicative of minimal dust absorption. The observed blue IRAC color and SED fitting suggest that z ∼ 10 galaxies have very young (few × 10 Myr) stellar populations, with 80% of stars being formed in the last ≲160 Myr (2 σ ). While an exciting result, the uncertainties on the SED are too large to allow us to place strong constraints on the presence of a nebular continuum in z ∼ 10 galaxies (as might be suggested by the blue [3.6]–[4.5] 0 mag color). The resulting sSFR is consistent with the specific accretion rate of dark matter halos, indicative of a star formation efficiency showing quite limited evolution at such early epochs.
Publisher: American Astronomical Society
Date: 31-03-2020
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: Public Library of Science (PLoS)
Date: 23-05-2019
Publisher: American Astronomical Society
Date: 09-2023
Publisher: American Astronomical Society
Date: 11-2022
Abstract: The first few 100 Myr at z 10 mark the last major uncharted epoch in the history of the universe, where only a single galaxy (GN-z11 at z ≈ 11) is currently spectroscopically confirmed. Here we present a search for luminous z 10 galaxies with JWST/NIRCam photometry spanning ≈1–5 μ m and covering 49 arcmin 2 from the public JWST Early Release Science programs (CEERS and GLASS). Our most secure candidates are two M UV ≈ −21 systems: GLASS-z12 and GLASS-z10. These galaxies display abrupt ≳1.8 mag breaks in their spectral energy distributions (SEDs), consistent with complete absorption of flux bluewards of Ly α that is redshifted to z = 12.4 − 0.3 + 0.1 and z = 10.4 − 0.5 + 0.4 . Lower redshift interlopers such as quiescent galaxies with strong Balmer breaks would be comfortably detected at σ in multiple bands where instead we find no flux. From SED modeling we infer that these galaxies have already built up ∼10 9 solar masses in stars over the ≲300–400 Myr after the Big Bang. The brightness of these sources enable morphological constraints. Tantalizingly, GLASS-z10 shows a clearly extended exponential light profile, potentially consistent with a disk galaxy of r 50 ≈ 0.7 kpc. These sources, if confirmed, join GN-z11 in defying number density forecasts for luminous galaxies based on Schechter UV luminosity functions, which require a survey area × larger than we have studied here to find such luminous sources at such high redshifts. They extend evidence from lower redshifts for little or no evolution in the bright end of the UV luminosity function into the cosmic dawn epoch, with implications for just how early these galaxies began forming. This, in turn, suggests that future deep JWST observations may identify relatively bright galaxies to much earlier epochs than might have been anticipated.
Publisher: American Astronomical Society
Date: 06-11-2009
Publisher: American Astronomical Society
Date: 05-05-2015
Publisher: American Astronomical Society
Date: 23-03-2201
Publisher: American Astronomical Society
Date: 08-06-2017
Publisher: American Astronomical Society
Date: 22-09-2015
Publisher: American Astronomical Society
Date: 26-10-2023
Publisher: American Astronomical Society
Date: 04-05-2018
Publisher: American Astronomical Society
Date: 13-03-2018
Publisher: American Astronomical Society
Date: 14-09-2017
Publisher: American Astronomical Society
Date: 14-03-2017
Publisher: American Astronomical Society
Date: 23-01-2018
Publisher: American Astronomical Society
Date: 02-2009
Publisher: American Astronomical Society
Date: 22-02-2021
Publisher: American Astronomical Society
Date: 13-04-2017
Start Date: 2014
End Date: 12-2017
Amount: $360,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2023
End Date: 12-2025
Amount: $375,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2023
End Date: 06-2027
Amount: $1,055,476.00
Funder: Australian Research Council
View Funded Activity