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Using a combination of Hubble Space Telescope (HST), JWST, and Atacama Large Millimeter/submillimeter Array (ALMA) data, we perform spatially resolved spectral energy distributions (SED) fitting of fourteen 4 < z < 6 ultraviolet (UV)-selected main-sequence galaxies targeted by the ALMA Large Program [C ii ] Resolved ISM in Star-forming Galaxies. We consistently model the emission from stars and dust in ∼0.5–1 kpc spatial bins to obtain maps of their physical properties. We find no offsets between the stellar masses (M *) and star formation rates (SFRs) derived from their global emission and those from adding up the values in our spatial bins, suggesting there is no bias of outshining by young stars on the derived global properties. We show that ALMA observations are important to derive robust parameter maps because they reduce the uncertainties in L dust (hence, AV and SFR). Using these maps, we explore the resolved star-forming main sequence for z ∼ 5 galaxies, finding that this relation persists in typical star-forming galaxies in the early Universe. We find less obscured star formation where the M * (and SFR) surface densities are highest, typically in the central regions, contrary to the global relation between these parameters. We speculate this could be caused by feedback driving gas and dust out of these regions. However, more observations of IR luminosities with ALMA are needed to verify this. Finally, we test empirical SFR prescriptions based on the UV+IR and [C ii ] line luminosity, finding they work well at the scales probed (approximately kiloparsec). Our work demonstrates the usefulness of joint HST-, JWST-, and ALMA-resolved SED modeling analyses at high redshift. [ABSTRACT FROM AUTHOR]

We present new multifrequency Atacama Large Millimeter/submillimeter Array (ALMA) continuum observations of the massive [ |$\log _{10}(M_\star /\mathrm{M}_\odot) = 10.3_{-0.2}^{+0.1}$| ], UV-luminous [ |$M_\mathrm{UV} = -21.7 \pm 0.2$| ] |$z=7.31$| galaxy REBELS-25 in Bands 3, 4, 5, and 9. Combining the new observations with previously taken data in Bands 6 and 8, we cover the dust continuum emission of the galaxy in six distinct bands – spanning rest-frame |$50-350\, \mu$| m – enabling simultaneous constraints on its dust mass (⁠|$M_\mathrm{dust}$|⁠), temperature (⁠|$T_\mathrm{dust}$|⁠), and emissivity index (⁠|$\beta _\mathrm{IR}$|⁠) via modified blackbody fitting. Given a fiducial model of optically thin emission, we infer a cold dust temperature of |$T_\mathrm{dust} = 32_{-6}^{+9}\,$|  K and a high dust mass of |$\log _{10}(M_\mathrm{dust}/\mathrm{M}_\odot) = 8.2_{-0.4}^{+0.6}$|⁠ , and moderately optically thick dust does not significantly alter these estimates. If we assume dust production is solely through supernovae (SNe), the inferred dust yield would be high, |$y = 0.7_{-0.4}^{+2.3}\, \mathrm{M}_\odot$| per SN. Consequently, we argue grain growth in the interstellar medium of REBELS-25 also contributes to its dust build-up. This is supported by the steep dust emissivity index |$\beta _\mathrm{IR} = 2.5 \pm 0.4$| we measure for REBELS-25, as well as by its high stellar mass, dense interstellar medium, and metal-rich nature. Our results suggest that constraining the dust emissivity indices of high-redshift galaxies is important not only to mitigate systematic uncertainties in their dust masses and obscured star formation rates, but also to assess if dust properties evolve across cosmic time. We present an efficient observing set-up to do so with ALMA, combining observations of the peak and Rayleigh–Jeans tail of the dust emission. [ABSTRACT FROM AUTHOR]

We present the morphological parameters and global properties of dust-obscured star formation in typical star-forming galaxies at z = 4–6. Among 26 galaxies composed of 20 galaxies observed by the Cycle-8 ALMA Large Program, CRISTAL, and 6 galaxies from archival data, we individually detect rest-frame 158 μm dust continuum emission from 19 galaxies, 9 of which are reported for the first time. The derived far-infrared luminosities are in the range log10LIR [L⊙] = 10.9 − 12.4, an order of magnitude lower than previously detected massive dusty star-forming galaxies (DSFGs). We find the average relationship between the fraction of dust-obscured star formation (fobs) and the stellar mass to be consistent with previous results at z = 4–6 in a mass range of log10M* [M⊙]∼9.5 − 11.0 and to show potential evolution from z = 6 − 9. The individual fobs exhibits significant diversity, and we find a potential correlation with the spatial offset between the dust and UV continuum, suggesting that inhomogeneous dust reddening may cause the source-to-source scatter in fobs. The effective radii of the dust emission are on average ∼1.5 kpc and are about two times more extended than those seen in rest-frame UV. The infrared surface densities of these galaxies (ΣIR ∼ 2.0 × 1010 L⊙ kpc−2) are one order of magnitude lower than those of DSFGs that host compact central starbursts. On the basis of the comparable contribution of dust-obscured and dust-unobscured star formation along with their similar spatial extent, we suggest that typical star-forming galaxies at z = 4 − 6 form stars throughout the entirety of their disks. [ABSTRACT FROM AUTHOR]

Combining the public JWST /NIRCam imaging programs CEERS, PRIMER, and JADES, spanning a total area of |$\sim 500\, {\rm arcmin}^2$|⁠ , we obtain a sample of |$\gt $| 30 000 galaxies at |$z_{\rm phot}\sim 4\!-\!9$| that allows us to perform a complete, rest-optical-selected census of the galaxy population at |$z\gt 3$|⁠. Comparing the stellar mass |$M_*$| and the UV-slope |$\beta$| distributions between JWST - and HST -selected samples, we generally find very good agreement and no significant biases. Nevertheless, JWST enables us to probe a new population of UV-red galaxies that was missing from previous HST -based Lyman-break galaxy (LBG) samples. We measure galaxy stellar mass functions (SMFs) at |$z\sim 4\!-\!9$| down to limiting masses of |$10^{7.5}\!-\!10^{8.5}\, {\rm M_\odot }$|⁠ , finding steep low-mass slopes over the entire redshift range, reaching values of |$\alpha \approx -2$| at |$z\gtrsim 6$|⁠. At the high-mass end, UV-red galaxies dominate at least out to |$z\sim 6$|⁠. The implied redshift evolution of the SMF suggests a rapid build-up of massive dust-obscured or quiescent galaxies from |$z\sim 6$| to |$z\sim 4$| as well as an enhanced efficiency of star formation towards earlier times (⁠|$z\gtrsim 6$|⁠). Finally, we show that the galaxy mass density grows by a factor |$\sim 20\times$| from |$z\sim 9$| to |$z\sim 4$|⁠. Our results emphasize the importance of rest-frame optically selected samples in inferring accurate distributions of physical properties and studying the mass build-up of galaxies in the first 1.5 Gyr of cosmic history. [ABSTRACT FROM AUTHOR]

We present specific star formation rates (sSFRs) for 40 ultraviolet (UV)-bright galaxies at z ∼ 7–8 observed as part of the Reionization Era Bright Emission Line Survey (REBELS) Atacama Large Millimeter/submillimeter Array (ALMA) large programme. The sSFRs are derived using improved star formation rate (SFR) calibrations and spectral energy distribution (SED)-based stellar masses, made possible by measurements of far-infrared (FIR) continuum emission and [C  ii ]-based spectroscopic redshifts. The median sSFR of the sample is |$18_{-5}^{+7}$|  Gyr−1, significantly larger than literature measurements lacking constraints in the FIR, reflecting the larger obscured SFRs derived from the dust continuum relative to that implied by the UV+optical SED. We suggest that such differences may reflect spatial variations in dust across these luminous galaxies, with the component dominating the FIR distinct from that dominating the UV. We demonstrate that the inferred stellar masses (and hence sSFRs) are strongly dependent on the assumed star formation history in reionization-era galaxies. When large sSFR galaxies (a population that is common at z > 6) are modelled with non-parametric star formation histories, the derived stellar masses can increase by an order of magnitude relative to constant star formation models, owing to the presence of a significant old stellar population that is outshined by the recent burst. The [C  ii ] line widths in the largest sSFR systems are often very broad, suggesting dynamical masses capable of accommodating an old stellar population suggested by non-parametric models. Regardless of these systematic uncertainties among derived parameters, we find that sSFRs increase rapidly toward higher redshifts for massive galaxies (9.6 < log (M */M⊙) < 9.8), evolving as (1 + z)1.7 ± 0.3, broadly consistent with expectations from the evolving baryon accretion rates. [ABSTRACT FROM AUTHOR]

We perform spectral energy distribution (SED) fitting to 711 luminous X-ray AGN at 0.7 < z < 4.5 using 10-bands of optical and infra-red photometric data for objects within XMM-SERVS. This fitting provided 510 reliable (reduced χ2 < 3) inferences on AGN and host galaxy properties. The AGN optical (3000 Å) luminosity inferred from SED-fitting is found to correlate with the measured X-ray (2–10 keV) luminosity, in good agreement with previous work. Using X-ray hardness as a proxy for AGN obscuration, we also study the differences in the host galaxy properties of obscured and unobscured AGNs. Both populations have consistent stellar masses (log10(M */ M ⊙)  = 10.88 |$\pm 0.09\, {\rm M}_\odot$| and log10(M */ M ⊙)  = 10.8 |$\pm 0.1\, {\rm M}_\odot$| for unobscured and obscured AGNs, respectively). We also find evidence for varying AGN emission line properties from a standard AGN template in 18.8 per cent of the sample with a reduced χ2 < 3 where the inclusion of an additional emission line strength free parameter was found to improve the quality of the fit. Comparison of these fits to SDSS spectra showed that emission line properties inferred from broad-band photometry were consistent with the results from spectroscopy for 91 per cent of objects. We find that the presence of weaker, more blueshifted emission lines as inferred from the SED fits are associated with more negative values of αox. While the correlation between the hardness of the ionizing SED and the emission line properties has been known for some time, we are able to derive this correlation purely from broad-band photometry. [ABSTRACT FROM AUTHOR]

We present the evolution in the number density and stellar mass functions of photometrically selected post-starburst galaxies in the UKIDSS Ultra Deep Survey, with redshifts of 0.5 < z < 2 and stellar masses log (M/M⊙) >10. We find that this transitionary species of galaxy is rare at all redshifts, contributing  ~5 per cent of the total population at z ~ 2, to <1 per cent by z ~ 0.5. By comparing the mass functions of quiescent galaxies to post-starburst galaxies at three cosmic epochs, we show that rapid quenching of star formation can account for 100 per cent of quiescent galaxy formation, if the post-starburst spectral features are visible for ~250 Myr. The flattening of the low-mass end of the quiescent galaxy stellar mass function seen at z ~ 1 can be entirely explained by the addition of rapidly quenched galaxies. Only if a significant fraction of post-starburst galaxies have features that are visible for longer than 250 Myr, or they acquire new gas and return to the star-forming sequence, can there be significant growth of the red sequence from a slower quenching route. The shape of the mass function of these transitory post-starburst galaxies resembles that of quiescent galaxies at z ~ 2, with a preferred stellar mass of log (M/M⊙)  ~10.6, but evolves steadily to resemble that of star-forming galaxies at z < 1. This leads us to propose a dual origin for post-starburst galaxies: (1) at z ≳ 2 they are exclusively massive galaxies that have formed the bulk of their stars during a rapid assembly period, followed by complete quenching of further star formation; (2) at z ≲ 1 they are caused by the rapid quenching of gas-rich star-forming galaxies, independent of stellar mass, possibly due to environment and/or gas-rich major mergers. [ABSTRACT FROM AUTHOR]