arXiv subjects

Rogier A. Windhorst

Publications and source records attributed to Rogier A. Windhorst.

At least 109 records · Page 6Linked to original sources

arXiv2024

LyC Leakers in the AstroSat UV Deep Field: Extreme UV emitters at the Cosmic Noon

We report the direct detection of Lyman Continuum (LyC) emission from 9 galaxies and 1 Active Galactic Nuclei (AGN) at $z$ $\sim$ 1.1-1.6 in the GOODS-North field using deep observations from the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat. The absolute escape fraction of the sources estimated from the far-ultraviolet (FUV) and H$α$ line luminosities using Monte Carlo (MC) analysis of two Inter-Galactic Medium (IGM) models span a range $\sim$ 10 - 55 $\%$. The restframe UV wavelength of the sources falls in the extreme-ultraviolet (EUV) regime $\sim$ 550-700 Å, the shortest LyC wavelength range probed so far. This redshift range remains devoid of direct detections of LyC emission due to the instrumental limitations of previously available facilities. With UVIT having a very low detector noise, each of these sources are detected with an individual signal-to-noise ratio (SNR) $>$ 3 while for the stack of six sources, we achieve an SNR $\sim$ 7.4. The LyC emission is seen to be offset from the optical centroids and extended beyond the UVIT PSF of 1.$^{\prime\prime}6$ in most of the sources. This sample fills an important niche between GALEX and Cosmic Origins Spectrograph (COS) at low-$z$, and HST WFC3 at high-$z$ and is crucial in understanding the evolution of LyC leakers.

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arXiv2024

A search for high-redshift direct-collapse black hole candidates in the PEARLS north ecliptic pole field

Direct-collapse black holes (DCBHs) of mass $\sim 10^4$-$10^5 {M}_\odot$ that form in HI-cooling halos in the early Universe are promising progenitors of the $\gtrsim 10^9 {M}_\odot$ supermassive black holes that fuel observed $z \gtrsim 7$ quasars. Efficient accretion of the surrounding gas onto such DCBH seeds may render them sufficiently bright for detection with the JWST up to $z\approx 20$. Additionally, the very steep and red spectral slope predicted across the $\approx 1$-5 $μ$m wavelength range of the JWST/NIRSpec instrument during their initial growth phase should make them photometrically identifiable up to very high redshifts. In this work, we present a search for such DCBH candidates across the 34 arcmin$^{2}$ in the first two spokes of the JWST cycle-1 PEARLS survey of the north ecliptic pole time-domain field covering eight NIRCam filters down to a maximum depth of $\sim$ 29 AB mag. We identify two objects with spectral energy distributions consistent with the Pacucci et al. (2016) DCBH models. However, we also note that even with data in eight NIRCam filters, objects of this type remain degenerate with dusty galaxies and obscured active galactic nuclei over a wide range of redshifts. Follow-up spectroscopy would be required to pin down the nature of these objects. Based on our sample of DCBH candidates and assumptions on the typical duration of the DCBH steep-slope state, we set a conservative upper limit of $\lesssim 5\times 10^{-4}$ comoving Mpc$^{-3}$ (cMpc$^{-3}$) on the comoving density of host halos capable of hosting DCBHs with spectral energy distributions similar to the Pacucci et al. (2016) models at $z\approx 6$-14.

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arXiv2024

JWST's PEARLS: Improved Flux Calibration for NIRCam

The Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS), a JWST GTO program, obtained a set of unique NIRCam observations that have enabled us to significantly improve the default photometric calibration across both NIRCam modules. The observations consisted of three epochs of 4-band (F150W, F200W, F356W, and F444W) NIRCam imaging in the Spitzer IRAC Dark Field (IDF). The three epochs were six months apart and spanned the full duration of Cycle 1. As the IDF is in the JWST continuous viewing zone, we were able to design the observations such that the two modules of NIRCam, modules A and B, were flipped by 180 degrees and completely overlapped each other's footprints in alternate epochs. We were therefore able to directly compare the photometry of the same objects observed with different modules and detectors, and we found significant photometric residuals up to ~ 0.05 mag in some detectors and filters, for the default version of the calibration files that we used (jwst_1039.pmap). Moreover, there are multiplicative gradients present in the data obtained in the two long-wavelength bands. The problem is less severe in the data reduced using the latest pmap (jwst_1130.pmap as of September 2023), but it is still present, and is non-negligible. We provide a recipe to correct for this systematic effect to bring the two modules onto a more consistent calibration, to a photometric precision better than ~ 0.02 mag.

astro-ph.IM↗

arXiv2024

Lyman Continuum Emission from AGN at 2.3$\lesssim$z$\lesssim$3.7 in the UVCANDELS Fields

We present the results of our search for Lyman continuum (LyC) emitting AGN at redshifts 2.3$\lesssim$z$\lesssim$4.9 from HST WFC3 F275W observations in the UVCANDELS fields. We also include LyC emission from AGN using HST WFC3 F225W, F275W, and F336W found in the ERS and HDUV data. We performed exhaustive queries of the Vizier database to locate AGN with high quality spectroscopic redshifts. In total, we found 51 AGN that met our criteria within the UVCANDELS and ERS footprints. Of these 51, we find 12 AGN had $\geq$4$σ$ detected LyC flux in the WFC3/UVIS images. Using space- and ground-based data from X-ray to radio, we fit the multi-wavelength photometric data of each AGN to a CIGALE SED and correlate various SED parameters to the LyC flux. KS-tests of the SED parameter distributions for the LyC-detected and non-detected AGN showed they are likely not distinct samples. However, we find that X-ray luminosity, star-formation onset age, and disk luminosity show strong correlations relative to their emitted LyC flux. We also find strong correlation of the LyC flux to several dust parameters, i.e., polar and toroidal dust emission, 6 $μm$ luminosity, and anti-correlation with metallicity and $A_{FUV}$. We simulate the LyC escape fraction ($f_{esc}$) using the CIGALE and IGM transmission models for the LyC-detected AGN and find an average $f_{esc}$$\simeq$18%, weighted by uncertainties. We stack the LyC flux of subsamples of AGN according to the wavelength continuum region in which they are detected and find no significant distinctions in their LyC emission, although our $sub-mm\ detected$ F336W sample shows the brightest stacked LyC flux. These findings indicate that LyC-production and -escape in AGN is more complicated than the simple assumption of thermal emission and a 100% escape fraction. Further testing of AGN models with larger samples than presented here is needed.

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arXiv2024

PEARLS: A Potentially Isolated Quiescent Dwarf Galaxy with a TRGB Distance of 30 Mpc

A wealth of observations have long suggested that the vast majority of isolated classical dwarf galaxies ($M_*=10^7$-$10^9$ M$_\odot$) are currently star-forming. However, recent observations of the large abundance of "Ultra-Diffuse Galaxies" beyond the reach of previous large spectroscopic surveys suggest that our understanding of the dwarf galaxy population may be incomplete. Here we report the serendipitous discovery of an isolated quiescent dwarf galaxy in the nearby Universe, which was imaged as part of the PEARLS GTO program. Remarkably, individual red-giant branch stars are visible in this near-IR imaging, suggesting a distance of $30\pm4$ Mpc, and a wealth of archival photometry point to an sSFR of $2\times10^{-11}$ yr$^{-1}$ and SFR of $4\times10^{-4}$ M$_\odot$ yr$^{-1}$. Spectra obtained with the Lowell Discovery Telescope find a recessional velocity consistent with the Hubble Flow and ${>}1500$ km/s separated from the nearest massive galaxy in SDSS, suggesting that this galaxy was either quenched from internal mechanisms or had a very high-velocity ($>1000$ km/s) interaction with a nearby massive galaxy in the past. This analysis highlights the possibility that many nearby quiescent dwarf galaxies are waiting to be discovered and that JWST has the potential to resolve them.

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arXiv2023

Star formation and AGN activity 500 Myr after the Big Bang: Insights from JWST

We consider the effect of including an active galactic nuclei (AGN) component when fitting spectral energy distributions of 109 spectroscopically confirmed $z\approx 3.5-12.5$ galaxies with JWST. Remarkably, we find that the resulting cosmic star formation history is $\approx 0.4$ dex lower at $z\gtrsim 9.5$ when an AGN component is included in the fitting. This alleviates previously reported excess star formation at $z\gtrsim 9.5$ compared to models based on typical baryon conversion efficiencies inside dark matter halos. We find that the individual stellar masses and star formation rates can be as much as $\approx 4$ dex lower when fitting with an AGN component. These results highlight the importance of considering both stellar mass assembly and supermassive black hole growth when interpreting the light distributions of among the first galaxies to ever exist.

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arXiv2023

MAGNIF: A Tentative Lensed Rotating Disk at $z=8.34$ detected by JWST NIRCam WFSS with Dynamical Forward Modeling

We report galaxy MACS0416-Y3 behind the lensing cluster MACSJ0416.1--2403 as a tentative rotating disk at $z=8.34$ detected through its [OIII]$\lambda5007$ emission in JWST NIRCam wide-field slitless spectroscopic observations. The discovery is based on our new grism dynamical modeling methodology for JWST NIRCam slitless spectroscopy, using the data from ``Median-band Astrophysics with the Grism of NIRCam in Frontier Fields'' (MAGNIF), a JWST Cycle-2 program. The [OIII]$\lambda5007$ emission line morphology in grism data shows velocity offsets compared to the F480M direct imaging, suggestive of rotation. Assuming a geometrically thin disk model, we constrain the rotation velocity of $v_{\rm rot}=58^{+53}_{-35}$ km s$^{-1}$ via forward modeling of the two-dimensional (2D) spectrum. We obtain the kinematic ratio of $v_{\rm rot}/σ_v=1.6^{+1.9}_{-0.9}$, where $σ_v$ is the velocity dispersion, in line with a quasi-stable thin disk. The resulting dynamical mass is estimated to be $\log(M_{\rm dyn}/M_{\odot})=8.4^{+0.5}_{-0.7}$. If the rotation confirmed, our discovery suggests that rotating gaseous disks may have already existed within 600 million years after Big Bang.

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arXiv2023

JWST's PEARLS: Transients in the MACS J0416.1-2403 Field

With its unprecedented sensitivity and spatial resolution, the James Webb Space Telescope (JWST) has opened a new window for time-domain discoveries in the infrared. Here we report observations in the only field that has received four epochs (spanning 126 days) of JWST NIRCam observations in Cycle 1. This field is towards MACS J0416.1-2403, which is a rich galaxy cluster at redshift z=0.4 and is one of the Hubble Frontier Fields. We have discovered 14 transients from these data. Twelve of these transients happened in three galaxies (with z=0.94, 1.01, and 2.091) crossing a lensing caustic of the cluster,and these transients are highly magnified by gravitational lensing. These 12 transients are likely of similar nature to those previously reported based on the Hubble Space Telescope (HST) data in this field, i.e., individual stars in the highly magnified arcs. However, these twelve could not have been found by HST because they are too red and too faint. The other two transients are associated with background galaxies (z=2.205 and 0.7093) that are only moderately magnified, and they are likely supernovae. They indicate a de-magnified supernova surface density, when monitored at a time cadence of a few months to a ~3--4 micron survey limit of AB ~ 28.5 mag, of ~0.5 per sq. arcmin integrated to z ~ 2. This survey depth is beyond the capability of HST but can be easily reached by JWST.

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arXiv2023

Lyman Continuum Emission from Spectroscopically Confirmed Ly$α$ Emitters at $z\sim3.1$

We present a study of Lyman continuum (LyC) emission in a sample of $\sim$150 Ly$α$ emitters (LAEs) at $z\approx3.1$ in the Subaru-XMM Deep Survey field. These LAEs were previously selected using the narrowband technique and spectroscopically confirmed with Ly$α$ equivalent widths (EWs) $\ge45$ Å. We obtain deep UV images using a custom intermediate-band filter $U_{\rm J}$ that covers a wavelength range of $3330 \sim 3650$ Å, corresponding to 810$\sim$890 Å in the rest frame. We detect 5 individual LyC galaxy candidates in the $U_{\rm J}$ band, and their escape fractions ($f_{\rm esc}$) of LyC photons are roughly between 40% and 80%. This supports a previous finding that a small fraction of galaxies may have very high $f_{\rm esc}$. We find that the $f_{\rm esc}$ values of the 5 LyC galaxies are not apparently correlated with other galaxy properties such as Ly$α$ luminosity and EW, UV luminosity and slope, and star-formation rate (SFR). This is partly due to the fact that these galaxies only represent a small fraction ($\sim3$%) of our LAE sample. For the remaining LAEs that are not detected in $U_{\rm J}$, we stack their $U_{\rm J}$-band images and constrain their average $f_{\rm esc}$. The upper limit of the average $f_{\rm esc}$ value is about 16%, consistent with the results in the literature. Compared with the non-LyC LAEs, the LyC LAEs tend to have higher Ly$α$ luminosities, Ly$α$ EWs, and SFRs, but their UV continuum slopes are similar to those of other galaxies.

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arXiv2023

UV-Bright Star-Forming Clumps and Their Host Galaxies in UVCANDELS at 0.5 $\leq$ z $\leq$ 1

Giant star-forming clumps are a prominent feature of star-forming galaxies (SFGs) and contain important clues on galaxy formation and evolution. However, basic demographics of clumps and their host galaxies remain uncertain. Using the HST/WFC3 F275W images from the Ultraviolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (UVCANDELS), we detect and analyze giant star-forming clumps in galaxies at 0.5 $\leq$ z $\leq$ 1, connecting two epochs when clumps are common (at cosmic high-noon, z $\sim$ 2) and rare (in the local universe). We construct a clump sample whose rest-frame 1600 Å luminosity is 3 times higher than the most luminous local HII regions (M$_{UV} \leq -$16 AB). In our sample, 35 $\pm$ 3$\%$ of low-mass galaxies (log[M$_{*}$/M$_{\odot}$] $<$ 10) are clumpy (i.e., containing at least one off-center clump). This fraction changes to 22 $\pm$ 3$\%$ and 22 $\pm$ 4$\%$ for intermediate (10 $\leq$ log[M$_{*}$/M$_{\odot}$] $\leq$ 10.5) and high-mass (log[M$_{*}$/M$_{\odot}$] $>$ 10.5) galaxies in agreement with previous studies. When compared to similar-mass non-clumpy SFGs, low- and intermediate-mass clumpy SFGs tend to have higher SFRs and bluer rest-frame U-V colors, while high-mass clumpy SFGs tend to be larger than non-clumpy SFGs. However, clumpy and non-clumpy SFGs have similar Sérsic index, indicating a similar underlying density profile. Furthermore, we investigate how UV luminosity of star-forming regions correlates with the physical properties of host galaxies. On average, more luminous star-forming regions reside in more luminous, smaller, and/or higher-specific SFR galaxies and are found closer to their hosts' galactic center.

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arXiv2023

Reaching for the stars -- JWST/NIRSpec spectroscopy of a lensed star candidate at $z=4.76$

We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of $z_{\mathrm{phot}}\simeq4.8$, previously detected in JWST/NIRCam imaging of the strong lensing (SL) cluster MACS J0647+7015 ($z=0.591$). The spectroscopic observation allows us to precisely measure the redshift of the host arc at $z_{\mathrm{spec}}=4.758\pm0.004$, and the star's spectrum displays clear Lyman- and Balmer-breaks commensurate with this redshift. A fit to the spectrum suggests a B-type super-giant star of surface temperature $T_{\mathrm{eff,B}}\simeq15000$ K with either a redder F-type companion ($T_{\mathrm{eff,F}}\simeq6250$K) or significant dust attenuation ($A_V\simeq0.82$) along the line of sight. We also investigate the possibility that this object is a magnified young globular cluster rather than a single star. We show that the spectrum is in principle consistent with a star cluster, which could also accommodate the lack of flux variability between the two epochs. However, the lack of a counter image and the strong upper limit on the size of the object from lensing symmetry, $r\lesssim0.5$ pc, could indicate that this scenario is somewhat less likely -- albeit not completely ruled out by the current data. The presented spectrum seen at a time when the Universe was only $\sim1.2$ Gyr old showcases the ability of JWST to study early stars through extreme lensing.

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arXiv2023

PEARLS: Near Infrared Photometry in the JWST North Ecliptic Pole Time Domain Field

We present Near-Infrared (NIR) ground-based Y, J, H, and K imaging obtained in the James Webb Space Telescope North Ecliptic Pole Time Domain Field (TDF) using the MMT-Magellan Infrared Imager and Spectrometer (MMIRS) on the MMT.These new observations cover a field of approximately 230 arcmin^2 in Y, H, and K and 313 arcmin^2 in J. Using Monte Carlo simulations we estimate a 1 sigma depth relative to the background sky of (Y, J, H, K}) = (23.80, 23.53, 23.13, 23.28) in AB magnitudes for point sources at a 95% completeness level. These observations are part of the ground-based effort to characterize this region of the sky, supplementing space-based data obtained with Chandra, NuSTAR, XMM, AstroSat, HST, and JWST. This paper describes the observations and reduction of the NIR imaging and combines these NIR data with archival imaging in the visible, obtained with the Subaru Hyper-Suprime-Cam, to produce a merged catalog of 57,501 sources. The new observations reported here, plus the corresponding multi-wavelength catalog, will provide a baseline for time-domain studies of bright sources in the TDF.

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arXiv2023

PEARLS: Low Stellar Density Galaxies in the El Gordo Cluster Observed with JWST

A full understanding of how unusually large "Ultra Diffuse Galaxies" (UDGs) fit into our conventional understanding of dwarf galaxies remains elusive, despite the large number of objects identified locally. A natural extension of UDG research is the study of similar galaxies at higher redshift to establish how their properties may evolve over time. However, this has been a challenging task given how severely systematic effects and cosmological surface brightness dimming inhibit our ability to study low-surface brightness galaxies at high-$z$. Here, we present an identification of low stellar surface density galaxies (LDGs), likely the progenitors of local UDGs, at moderate redshift with deep near-IR observations of the El Gordo cluster at $z = 0.87$ with JWST. By stacking 8 NIRCAM filters, we are able to achieve an apparent surface brightness sensitivity of $24.59$ mag arcsec$^{-2}$, faint enough to be complete to the bright end of the LDG population. Our analysis identifies significant differences between this population and local UDGs, such as their color and size distributions, which suggest that UDG progenitors are bluer and more extended at high-$z$ than at $z = 0$. This suggests that multiple mechanisms are responsible for UDG formation and that prolonged transformation of cluster dwarfs is not a primary UDG formation mechanism at high-$z$. Furthermore, we find a slight overabundance of LDGs in El Gordo, and, in contrast to findings in local clusters, our analysis does not show a deficit of LDGs in the center of El Gordo, implying that tidal destruction of LDGs is significant between $z = 0.87$ and $z = 0$.

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arXiv2023

EPOCHS VII: Discovery of high redshift ($6.5 < z < 12$) AGN candidates in JWST ERO and PEARLS data

We present an analysis of a sample of robust high redshift galaxies selected photometrically from the `blank' fields of the Prime Extragalactic Areas for Reionization Science (PEARLS) survey and Early Release Observations (ERO) data of the James Webb Space Telescope (JWST) with the aim of selecting candidate high redshift active galactic nuclei (AGN). Sources were identified from the parent sample using a threefold selection procedure, which includes spectral energy distribution (SED) fitting to identify sources that are best fitted by AGN SED templates, a further selection based on the relative performance of AGN and non-AGN models, and finally morphological fitting to identify compact sources of emission, resulting in a purity-oriented procedure. Using this procedure, we identify a sample of nine AGN candidates at $6.5 < z < 12$, from which we constrain their physical properties as well as measure a lower bound on the AGN fraction in this redshift range of $5 \pm 1$\%. As this is an extreme lower limit due to our focus on purity and our SEDs being calibrated for unobscured Type 1 AGN, this demonstrates that AGN are perhaps quite common at this early epoch. The rest-frame UV colors of our candidate objects suggest that these systems are potentially candidate obese black hole galaxies (OBG), or AGN with very little galaxy component. We also investigate emission from our sample sources from fields overlapping with Chandra and VLA surveys, allowing us to place X-ray and 3 GHz radio detection limits on our candidates. Of note is a $z = 11.9$ candidate source exhibiting an abrupt morphological shift in the reddest band as compared to the bluer bands, indicating a potential merger or an unusually strong outflow.

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arXiv2023

High-Redshift Galaxy Candidates at $z = 9-10$ as Revealed by JWST Observations of WHL0137-08

We report the discovery of four galaxy candidates observed 450 - 600 Myr after the Big Bang with photometric redshifts between z ~ 8.3 - 10.2 measured using the JWST NIRCam imaging of the galaxy cluster WHL0137-08 observed in 8 filters spanning 0.8-5.0 micron, plus 9 Hubble filters spanning 0.4-1.7 micron. One candidate is gravitationally lensed with a magnification of ~8, while the other three are located in a nearby NIRCam module with expected magnifications of <~ 1.1. Using SED fitting, we estimate the stellar masses of these galaxies are typically in the range log M*/Msun = 8.3 - 8.7. All appear young with mass-weighted ages < 240 Myr, low dust content A_V < 0.15 mag, and specific star formation rates sSFR ~0.25 - 10 /Gyr for most. One z ~ 9 candidate is consistent with an age < 5 Myr and a sSFR ~10 /Gyr, as inferred from a strong F444W excess, implying [OIII]+H-beta rest-frame equivalent width ~2000 Angstrom, although an older z ~ 10 object is also allowed. Another z ~ 9 candidate is lensed into an arc 2.4 arcsec long with a magnification of ~8. This arc is the most spatially-resolved galaxy at z ~ 9 known to date, revealing structures ~30 pc across. Follow-up spectroscopy of WHL0137-08 with JWST/NIRSpec will be useful to spectroscopically confirm these high-redshift galaxy candidates and to study their physical properties in more detail.

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arXiv2023

Are JWST/NIRCam color gradients in the lensed z=2.3 dusty star-forming galaxy El Anzuelo due to central dust attenuation or inside-out galaxy growth?

Gradients in the mass-to-light ratio of distant galaxies impede our ability to characterize their size and compactness. The long-wavelength filters of $JWST$'s NIRCam offer a significant step forward. For galaxies at Cosmic Noon ($z\sim2$), this regime corresponds to the rest-frame near-infrared, which is less biased towards young stars and captures emission from the bulk of a galaxy's stellar population. We present an initial analysis of an extraordinary lensed dusty star-forming galaxy (DSFG) at $z=2.3$ behind the $El~Gordo$ cluster ($z=0.87$), named $El~Anzuelo$ ("The Fishhook") after its partial Einstein-ring morphology. The FUV-NIR SED suggests an intrinsic star formation rate of $81^{+7}_{-2}~M_\odot~{\rm yr}^{-1}$ and dust attenuation $A_V\approx 1.6$, in line with other DSFGs on the star-forming main sequence. We develop a parametric lens model to reconstruct the source-plane structure of dust imaged by the Atacama Large Millimeter/submillimeter Array, far-UV to optical light from $Hubble$, and near-IR imaging with 8 filters of $JWST$/NIRCam, as part of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) program. The source-plane half-light radius is remarkably consistent from $\sim 1-4.5~μ$m, despite a clear color gradient where the inferred galaxy center is redder than the outskirts. We interpret this to be the result of both a radially-decreasing gradient in attenuation and substantial spatial offsets between UV- and IR-emitting components. A spatial decomposition of the SED reveals modestly suppressed star formation in the inner kiloparsec, which suggests that we are witnessing the early stages of inside-out quenching.

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arXiv2023

JWST's PEARLS: Mothra, a new kaiju star at z=2.091 extremely magnified by MACS0416, and implications for dark matter models

We report the discovery of Mothra, an extremely magnified monster star, likely a binary system of two supergiant stars, in one of the strongly lensed galaxies behind the galaxy cluster MACS0416. The star is in a galaxy with spectroscopic redshift $z=2.091$ in a portion of the galaxy that is parsecs away from the cluster caustic. The binary star is observed only on the side of the critical curve with negative parity but has been detectable for at least eight years, implying the presence of a small lensing perturber. Microlenses alone cannot explain the earlier observations of this object made with the Hubble Space Telescope. A larger perturber with a mass of at least $10^4$\,\Msun\ offers a more satisfactory explanation. Based on the lack of perturbation on other nearby sources in the same arc, the maximum mass of the perturber is $M< 2.5\times10^6$\,\Msun, making it the smallest substructure constrained by lensing above redshift 0.3. The existence of this millilens is fully consistent with the expectations from the standard cold dark matter model. On the other hand, the existence of such small substructure in a cluster environment has implications for other dark matter models. In particular, warm dark matter models with particle masses below 8.7\,keV are excluded by our observations. Similarly, axion dark matter models are consistent with the observations only if the axion mass is in the range $0.5\times10^{-22}\, {\rm eV} < m_a < 5\times10^{-22}\, {\rm eV}$.

astro-ph.CO↗

arXiv2023

Hidden giants in JWST's PEARLS: An ultra-massive z=4.26 sub-millimeter galaxy that is invisible to HST

We present a multi-wavelength analysis using SMA, JCMT, NOEMA, JWST, HST, and SST of two dusty strongly star-forming galaxies, 850.1 and 850.2, seen through the massive cluster lens A1489. These SMA-located sources both lie at z=4.26 and have bright dust continuum emission, but 850.2 is a UV-detected Lyman-break galaxy, while 850.1 is undetected at <2um, even with deep JWST/NIRCam observations. We investigate their stellar, ISM, and dynamical properties, including a pixel-level SED analysis to derive sub-kpc-resolution stellar-mass and Av maps. We find that 850.1 is one of the most massive and highly obscured, Av~5, galaxies known at z>4 with M*~10^11.8 Mo (likely forming at z>6), and 850.2 is one of the least massive and least obscured, Av~1, members of the z>4 dusty star-forming population. The diversity of these two dust-mass-selected galaxies illustrates the incompleteness of galaxy surveys at z>3-4 based on imaging at <2um, the longest wavelengths feasible from HST or the ground. The resolved mass map of 850.1 shows a compact stellar mass distribution, Re(mass)~1kpc, but its expected evolution to z~1.5 and then z~0 matches both the properties of massive, quiescent galaxies at z~1.5 and ultra-massive early-type galaxies at z~0. We suggest that 850.1 is the central galaxy of a group in which 850.2 is a satellite that will likely merge in the near future. The stellar morphology of 850.1 shows arms and a linear bar feature which we link to the active dynamical environment it resides within.

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