Search

Aims. This paper utilises the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) to extend the observational studies of dust and polycyclic aromatic hydrocarbon (PAH) emission to a new mass and star formation rate (SFR) parameter space beyond our local Universe. The combination of fully sampled spectral energy distributions (SEDs) with multiple mid-infrared (mid-IR) bands and the unprecedented sensitivity of MIRI allows us to investigate dust obscuration and PAH behaviour from z = 0.7 up to z = 2 in typical main-sequence galaxies. Our focus is on constraining the evolution of PAH strength and the dust-obscured luminosity fraction before and during cosmic noon, the epoch of peak star formation activity in the Universe. Methods. In this study, we utilise MIRI multi-band imaging data from the SMILES survey (5 to 25 μm), complemented with NIRCam photometry from the JADES survey (1 to 5 μm), available HST photometry (0.4 to 0.9 μm), and spectroscopic redshifts from the FRESCO and JADES surveys in GOODS-S for 443 star-forming (without dominant active galactic nucleus (AGN)) galaxies at z = 0.7 − 2.0. This redshift range was chosen to ensure that the MIRI data cover mid-IR dust emission. Our methodology involved employing ultraviolet (UV) to IR energy balance SED fitting to robustly constrain the fraction of dust mass in PAHs and dust-obscured luminosity. Additionally, we inferred dust sizes from MIRI 15 μm imaging data, enhancing our understanding of the physical characteristics of dust within these galaxies. Results. We find a strong correlation between the fraction of dust in PAHs (PAH fraction, qPAH) with stellar mass. Moreover, the sub-sample with robust qPAH measurements (N = 216) shows a similar behaviour between qPAH and gas-phase metallicity to that at z ∼ 0, suggesting a universal relation: qPAH is constant (∼3.4%) above a metallicity of Z ∼ 0.5 Z⊙ and decreases to < 1% at metallicities ≲0.3 Z⊙. This indicates that metallicity is a good indicator of the interstellar medium properties that affect the balance between the formation and destruction of PAHs. The lack of a redshift evolution from z ∼ 0 − 2 also implies that above Z ∼ 0.5 Z⊙ the PAH emission effectively traces obscured luminosity and the previous locally calibrated PAH-SFR calibrations remain applicable in this metallicity regime. We observe a strong correlation between the obscured UV luminosity fraction (ratio of obscured to total luminosity) and stellar mass. Above the stellar mass of M* > 5 × 109M⊙, on average, more than half of the emitted luminosity is obscured, while there exists a non-negligible population of lower-mass galaxies with > 50% obscured fractions. At a fixed mass, the obscured fraction correlates with SFR surface density. This is a result of higher dust covering fractions in galaxies with more compact star-forming regions. Similarly, galaxies with high IRX (IR to UV luminosity) at a given mass or UV continuum slope (β) tend to have higher ΣSFR and shallower attenuation curves, owing to their higher effective dust optical depths and more compact star-forming regions. [ABSTRACT FROM AUTHOR]

We present results from the JWST First Reionization Epoch Spectroscopically Complete Observations survey on the star-forming sequence (SFS) of galaxies at 1.0 < z < 1.7, around the peak of the cosmic star formation history. Star formation rates (SFRs) are measured from the redshifted, relatively dust-insensitive Paschen- α emission line, and stellar mass measurements include the F444W (4.4 μ m; rest-frame H) band. We find SFRs of galaxies with log(M */ M ⊙) > 9.5 that are lower than found in many earlier studies by up to 0.6 dex, but in good agreement with recent results obtained with the Prospector fitting framework. The difference (log(SFR(Pa α)-SFR(Prospector)) is −0.09 ± 0.04 dex at 1010−11 M ⊙. We also measure the empirical relation between Paschen- α luminosity and rest-frame H- band magnitude and find that the scatter is only 0.04 dex lower than that of the SFR– M * relation and is much lower than the systematic differences among relations in the literature due to various methods of converting observed measurements to physical properties. We additionally identify examples of sources—that, with standard cutoffs via the UVJ diagram, would be deemed quiescent—with significant (log(sSFR)> −11 yr−1), typically extended, Paschen- α emission. Our results may be indicative of the potential unification of methods used to derive the SFS with careful selection of star-forming galaxies and independent SFR and stellar mass indicators. [ABSTRACT FROM AUTHOR]

Star-forming galaxies (SFGs) adhere to a surprisingly tight scaling relation of dust attenuation parametrized by the infrared excess (IRX≡ L IR/ L UV), being jointly determined by the star formation rate (SFR), galaxy size (R e), metallicity (Z /Z⊙), and axial ratio (b / a). We examine how these galaxy parameters determine the effective dust attenuation and give rise to the universal IRX relation, utilizing a simple two-component star-dust geometry model in which dust in the dense and diffuse interstellar medium (ISM) follows exponential mass density profiles, connected with but not necessarily identical to the stellar mass profiles. Meanwhile, empirical relations are adopted to link galaxy properties, including the gas–star formation relation, the dust-to-stellar size relation, as well as the dust-to-gas ratio versus metallicity relation. By fitting a large sample of local SFGs with the model, we obtain the best-fitting model parameters as a function of metallicity, showing that the two-component geometry model is able to successfully reproduce the dependence of IRX on SFR, R e, b / a at given Z /Z⊙, as well as the dependence of power-law indices on metallicity. Moreover, we also retrieve constraints on the model geometry parameters, including the optical depth of birth clouds (BCs), BC-to-total dust mass fraction, BC covering factor of UV-emitting stars, and star-to-total dust disc radius ratio, which all evolve with galaxy metallicity. Finally, a consistent picture of how the star-dust geometry in SFGs evolves with galaxy metallicity is discussed. [ABSTRACT FROM AUTHOR]

We present a protocluster search covering z ∼ 3 to z ∼ 5 based on the combination of the Hyper SuprimeCam Subaru Strategic Programme and the CFHT Large Area U -band Deep Survey. We identify about 30 protocluster candidates per unit redshift over the |$\sim 25\, \mathrm{deg^2}$| area of the Deep/UltraDeep layer. Protocluster candidates are selected as regions with a significantly enhanced surface density of dropout galaxies. With this large sample, we characterize the properties of their individual member galaxies. We compare the number counts of dropout galaxies in protocluster candidates with that of coeval field galaxies. Rest-frame ultraviolet (UV) bright galaxies are overabundant in protocluster candidates, a trend seen across the full redshift range studied. We do not find evidence for their spatial distribution within protocluster candidates to be distinct from their fainter counterparts, nor for their UV colour to be different from that of field galaxies with the same brightness. Cosmological simulations predict this bright-end excess, with the main cause being a richer population of massive galaxies, with only a minor contribution from an enhancement in star formation activity (and therefore UV emission) at fixed mass. U -to- K SED modelling of our observed samples supports this interpretation. This environmental differentiation in number counts is already in place at z ∼ 5, with no significant redshift dependence over the range in lookback times probed. These observational results and model predictions suggest that the cosmic clock is ahead in high-density environments. [ABSTRACT FROM AUTHOR]

We compare ionized gas and stellar kinematics of 16 star-forming galaxies (log (M ⋆/ M ⊙) = 9.7–11.2, SFR =6 − 86 M⊙ yr−1) at z ∼ 1 using near-infrared integral field spectroscopy (IFS) of Hα emission from the KMOS3D (the K-band Multi-Object Spectrograph 3D) survey and optical slit spectroscopy of stellar absorption and gas emission from the LEGA-C (Large Early Galaxy Astrophysics Census) survey. Hα is dynamically colder than stars, with higher disc rotation velocities (by ∼45 per cent) and lower disc velocity dispersions (by a factor ∼2). This is similar to trends observed in the local Universe. We find higher rotational support for Hα relative to [O  ii ], potentially explaining systematic offsets in kinematic scaling relations found in the literature. Regarding dynamical mass measurements, for six galaxies with cumulative mass profiles from Jeans Anisotropic Multi-Gaussian Expansion (JAM) models the Hα dynamical mass models agree remarkably well out to ∼10 kpc for all but one galaxy (average |$\Delta M_{\rm dyn}(R_{e,\rm F814W})\lt 0.1$| dex). Simpler dynamical mass estimates based on integrated stellar velocity dispersion are less accurate (standard deviation 0.24 dex). Differences in dynamical mass estimates are larger, for example, for galaxies with stronger misalignments of the Hα kinematic major axis and the photometric position angle, highlighting the added value of IFS observations for dynamics studies. The good agreement between the JAM and the dynamical models based on Hα kinematics at z ∼ 1 corroborates the validity of dynamical mass measurements from Hα IFS observations, which can be more easily obtained for higher redshift galaxies. [ABSTRACT FROM AUTHOR]

The relatively red wavelength range (4800–9300 Å) of the VLT Multi Unit Spectroscopic Explorer (MUSE) limits which metallicity diagnostics can be used; in particular excluding those requiring the [ |${\rm O\, {\small II}}$| ]λλ3726,29 doublet. We assess various strong line diagnostics by comparing to sulphur |$T_{\rm {\it e}}$| -based metallicity measurements for a sample of 671 H  ii regions from 36 nearby galaxies from the MUSE Atlas of Disks (MAD) survey. We find that the O3N2 and N2 diagnostics return a narrower range of metallicities that lie up to ∼0.3 dex below |$T_{\rm {\it e}}$| -based measurements, with a clear dependence on both metallicity and ionization parameter. The N2S2H α diagnostic shows a near-linear relation with the |$T_{\rm {\it e}}$| -based metallicities, although with a systematic downward offset of ∼0.2 dex, but no clear dependence on ionization parameter. These results imply that the N2S2H α diagnostic produces the most reliable results when studying the distribution of metals within galaxies with MUSE. On sub-H  ii region scales, the O3N2 and N2 diagnostics measure metallicity decreasing towards the centres of H  ii regions, contrary to expectations. The S-calibration and N2S2H α diagnostics show no evidence of this, and show a positive relationship between ionization parameter and metallicity at |$12 + \log (\rm {O/H})$| > 8.4, implying the relationship between ionization parameter and metallicity differs on local and global scales. We also present hiidentify , a python tool developed to identify H  ii regions within galaxies from H α emission maps. All segmentation maps and measured emission line strengths for the 4408 H  ii regions identified within the MAD sample are available to download. [ABSTRACT FROM AUTHOR]

Most massive galaxies are thought to have formed their dense stellar cores in early cosmic epochs (1-3). Previous studies have found galaxies with high gas velocity dispersions (4) or small apparent sizes (5-7), but so far no objects have been identified with both the stellar structure and the gas dynamics of a forming core. Here we report a candidate core in the process of formation 11 billion years ago, at redshift z = 2.3. This galaxy, GOODS-N-774, has a stellar mass of 100 billion solar masses, a half-light radius of 1.0 kiloparsecs and a star formation rate of [90.sup.+45.sub.-20] solar masses per year. The star-forming gas has a velocity dispersion of 317 ± 30 kilometres per second. This is similar to the stellar velocity dispersions of the putative descendants of GOODSN-774, which are compact quiescent galaxies at z [approximately equals to] 2 (refs 8-11) and giant elliptical galaxies in the nearby Universe. Galaxies such as GOODS-N-774 seem to be rare; however, from the star formation rate and size of this galaxy we infer that many star-forming cores may be heavily obscured, and could be missed in optical and near-infrared surveys., We identified the candidate forming core, GOODS-N-774, using the 3D-HST catalogues in the five CANDELS (Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey) fields (12). GOODS-N-774 has a circularized effective radius [...]

We study the intrinsic 3D shapes of quiescent galaxies over the last half of cosmic history based on their axial ratio distribution. To this end, we construct a sample of unprecedented size, exploiting multiwavelength u -to- Ks photometry from the deep wide-area surveys KiDS+VIKING paired with high-quality i -band imaging from HSC-SSP. The dependences of the shapes on mass, redshift, photometric bulge prominence and environment are considered. For comparison, the intrinsic shapes of quenched galaxies in the IllustrisTNG simulations are analysed and contrasted with their formation history. We find that over the full 0 < z < 0.9 range, and in both simulations and observations, spheroidal 3D shapes become more abundant at |$M_* \gt 10^{11}\, \mathrm{M}_{\odot }$|⁠ , with the effect being most pronounced at lower redshifts. In TNG, the most massive galaxies feature the highest ex situ stellar mass fractions, pointing to violent relaxation via mergers as the mechanism responsible for their 3D shape transformation. Larger differences between observed and simulated shapes are found at low to intermediate masses. At any mass, the most spheroidal quiescent galaxies in TNG feature the highest bulge mass fractions, and, conversely, observed quiescent galaxies with the highest bulge-to-total ratios are found to be intrinsically the roundest. Finally, we detect an environmental influence on galaxy shape, at least at the highest masses, such that at fixed mass and redshift, quiescent galaxies tend to be rounder in denser environments. [ABSTRACT FROM AUTHOR]

This paper investigates the neutral gas phase of galactic winds via the Na  i Dλλ5890, 5895Å feature within z ∼ 0.04 MaNGA galaxies and directly compares their incidence and strength to the ionized winds detected within the same parent sample. We find evidence for neutral outflows in 127 galaxies (∼5 per cent of the analysed line-emitting sample). |${\rm Na\, \small {\rm I}\ D}$| winds are preferentially seen in galaxies with dustier central regions and both wind phases are more often found in systems with elevated star formation rate (SFR) surface densities, especially when there has been a recent upturn in the star formation activity according to the |$\rm SFR_{5 \, Myr}/SFR_{800 \, Myr}$| parameter. We find the ionized outflow kinematics to be in line with what we measure in the neutral phase. This demonstrates that, despite their small contributions to the total outflow mass budget, there is value to collecting empirical measurements of the ionized wind phase to provide information on bulk motion in the outflow. Depending on dust corrections applied to the ionized gas diagnostics, the neutral phase has ∼1.2−1.8 dex higher mass outflow rates (⁠|$\dot{M}_{\rm out}$|⁠), on average, compared to the ionized phase. We quantify scaling relations between |$\dot{M}_{\rm out}$| and the strengths of the physical wind drivers (SFR, L AGN). Using a radial–azimuthal stacking method, and by considering inclination dependencies, we find results consistent with biconical outflows orthogonal to the disc plane. Our work complements other multiphase outflow studies in the literature that consider smaller samples, more extreme objects, or proceed via stacking of larger samples. [ABSTRACT FROM AUTHOR]

While the slope of the dust attenuation curve (δ) is found to correlate with effective dust attenuation (A V) as obtained through spectral energy distribution (SED) fitting, it remains unknown how the fitting degeneracies shape this relation. We examine the degeneracy effects by fitting SEDs of a sample of local star-forming galaxies (SFGs) selected from the Galaxy And Mass Assembly survey, in conjunction with mock galaxy SEDs of known attenuation parameters. A well-designed declining starburst star formation history is adopted to generate model SED templates with intrinsic UV slope (β0) spanning over a reasonably wide range. The best-fitting β0 for our sample SFGs shows a wide coverage, dramatically differing from the limited range of β0 < −2.2 for a starburst of constant star formation. Our results show that strong degeneracies between β0, δ, and A V in the SED fitting induce systematic biases leading to a false A V–δ correlation. Our simulation tests reveal that this relationship can be well reproduced even when a flat A V–δ relation is taken to build the input model galaxy SEDs. The variations in best-fitting δ are dominated by the fitting errors. We show that assuming a starburst with constant star formation in SED fitting will result in a steeper attenuation curve, smaller degeneracy errors, and a stronger A V–δ relation. Our findings confirm that the A V–δ relation obtained through SED fitting is likely driven by the systematic biases induced by the fitting degeneracies between β0, δ, and A V. [ABSTRACT FROM AUTHOR]

In this work, we investigate the strength and impact of ionized gas outflows within z ∼ 0.04 MaNGA galaxies. We find evidence for outflows in 322 galaxies (⁠|$12{{\ \rm per\ cent}}$| of the analysed line-emitting sample), 185 of which show evidence for hosting an active galactic nucleus (AGN). Most outflows are centrally concentrated with a spatial extent that scales sublinearly with R e. The incidence of outflows is enhanced at higher masses, central surface densities, and deeper gravitational potentials, as well as at higher star formation rate (SFR) and AGN luminosity. We quantify strong correlations between mass outflow rates and the mechanical drivers of the outflow of the form |$\dot{M}_{\rm out} \propto \rm SFR^{0.97}$| and |$\dot{M}_{\rm out} \propto L_{\rm AGN}^{0.55}$|⁠. We derive a master scaling relation describing the mass outflow rate of ionized gas as a function of M ⋆, SFR, R e, and L AGN. Most of the observed winds are anticipated to act as galactic fountains, with the fraction of galaxies with escaping winds increasing with decreasing potential well depth. We further investigate the physical properties of the outflowing gas finding evidence for enhanced attenuation in the outflow, possibly due to metal-enriched winds, and higher excitation compared to the gas in the galactic disc. Given that the majority of previous studies have focused on more extreme systems with higher SFRs and/or more luminous AGN, our study provides a unique view of the non-gravitational gaseous motions within 'typical' galaxies in the low-redshift Universe, where low-luminosity AGN and star formation contribute jointly to the observed outflow phenomenology. [ABSTRACT FROM AUTHOR]

The Cepheid Leavitt Law (LL), also known as the Period–Luminosity relation, is a crucial tool for assembling the cosmic distance ladder. By combining data from the OGLE-IV catalogue with mid-infrared photometry from the Spitzer Space Telescope , we have determined the 3.6 and 4.5  |$\mu$| m LLs for the Magellanic Clouds using ∼5000 fundamental-mode classical Cepheids. Mean magnitudes were determined using a Monte Carlo Markov Chain (MCMC) template fitting procedure, with template light curves constructed from a subsample of these Cepheids with fully phased, well-sampled light curves. The dependence of the Large Magellanic Cloud LL coefficients on various period cuts was tested, in addition to the linearity of the relationship. The zero-point of the LL was calibrated using the parallaxes of Milky Way Cepheids from the Hubble Space Telescope and Gaia Data Release 2. Our final calibrated relations are M [3.6] = −3.246(±0.008)(log (P) − 1.0) − 5.784(±0.030) and M [4.5] = −3.162(±0.008)(log (P) − 1.0) − 5.751(±0.030). [ABSTRACT FROM AUTHOR]

We study the dynamical properties of massive quiescent galaxies at 1.4 < z < 2.1 using deep Hubble Space Telescope WFC3/F160W imaging and a combination of literature stellar velocity dispersion measurements and new near-infrared spectra obtained using the K-band Multi Object Spectrograph (KMOS) on the ESO Very Large Telescope. We use these data to show that the typical dynamical-to-stellar mass ratio has increased by ∼0.2 dex from z = 2 to the present day, and we investigate this evolution in the context of possible changes in the stellar initial mass function (IMF) and/or fraction of dark matter contained within the galaxy effective radius, fDM[e]. Comparing our high-redshift sample to their likely descendants at low redshift, we find that fDM[e] has increased by a factor of more than 4 since z ≈ 1.8, from fDM[e] = 6.6% ± 1.0% to ∼24%. The observed increase appears robust to changes in the methods used to estimate dynamical masses or match progenitors and descendants. We quantify possible variation of the stellar IMF through the offset parameter α, defined as the ratio of dynamical mass in stars to the stellar mass estimated using a Chabrier IMF. We demonstrate that the correlation between stellar velocity dispersion and α reported among quiescent galaxies at low redshift is already in place at z = 2, and we argue that subsequent evolution through (mostly minor) merging should act to preserve this relation while contributing significantly to galaxies' overall growth in size and stellar mass. [ABSTRACT FROM AUTHOR]

Ever deeper and wider look-back surveys have led to a fairly robust outline of the cosmic star-formation history, which culminated around ; this period is often nicknamed "cosmic noon." Our knowledge about star-forming galaxies at these epochs has dramatically advanced from increasingly complete population censuses and detailed views of individual galaxies. We highlight some of the key observational insights that influenced our current understanding of galaxy evolution in the equilibrium growth picture: Scaling relations between galaxy properties are fairly well established among massive galaxies at least out to , pointing to regulating mechanisms already acting on galaxy growth. Resolved views reveal that gravitational instabilities and efficient secular processes within the gas- and baryon-rich galaxies at play an important role in the early buildup of galactic structure. Ever more sensitive observations of kinematics at are probing the baryon and dark matter budget on galactic scales and the links between star-forming galaxies and their likely descendants. Toward higher masses, massive bulges, dense cores, and powerful AGNs and AGN-driven outflows are more prevalent and likely play a role in quenching star formation. We outline emerging questions and exciting prospects for the next decade with upcoming instrumentation, including the James Webb Space Telescope and the next generation of extremely large telescopes. [ABSTRACT FROM AUTHOR]

Resolved observations of star-forming galaxies at cosmic noon with the Hubble Space Telescope and large ground-based facilities provide a view on the spatial distribution of stars, gas and dust, and probe gaseous motions revealing the central gravitational potential and local feedback processes at play. In this paper, we review recent insights gained from such observations, with an emphasis on results obtained through optical/near-infrared imaging and imaging spectroscopy. Their context and implications are documented more fully in a forthcoming review article by Förster Schreiber & Wuyts (in prep). [ABSTRACT FROM AUTHOR]

HST and integral-field spectroscopic observations of star-forming galaxies at cosmic noon provide a view on the spatial distribution of stars, gas and dust, and probe gaseous motions revealing the central gravitational potential and local feedback processes at play. In this paper, we review recent insights gained from such observations, with an emphasis on results obtained through near-infrared imaging spectroscopy. Their context and implications are documented more fully in a forthcoming review article by Förster Schreiber & Wuyts (in prep). [ABSTRACT FROM AUTHOR]

We compare the infrared excess (IRX) and Balmer decrement () as dust attenuation indicators in relation to other galaxy parameters using a sample of ∼32,000 local star-forming galaxies (SFGs) carefully selected from the Sloan Digital Sky Survey, the Galaxy Evolution Explorer, and the Wide-field Infrared Survey Explore. While at fixed , IRX turns out to be independent on galaxy stellar mass, the Balmer decrement does show a strong mass dependence at fixed IRX. We find the discrepancy, parameterized by the color excess ratio , is not dependent on the gas-phase metallicity and axial ratio, but on the specific star formation rate (SSFR) and galaxy size (Re) following. This finding reveals that the nebular attenuation as probed by the Balmer decrement becomes increasingly larger than the global (stellar) attenuation of SFGs with decreasing SSFR surface density. This can be understood in the context of an enhanced fraction of intermediate-age stellar populations that are less attenuated by dust than the H ii region-traced young population, in conjunction with a decreasing dust opacity of the diffuse interstellar matter when spreading over a larger spatial extent. Once the SSFR surface density of an SFG is known, the conversion between attenuation of nebular and stellar emission can be well estimated using our scaling relation. [ABSTRACT FROM AUTHOR]

We investigate dust obscuration as parametrized by the infrared excess IRX ≡  L IR/ L UV in relation to global galaxy properties, using a sample of ∼32 000 local star-forming galaxies (SFGs) selected from SDSS (Sloan Digital Sky Survey), GALEX (Galaxy Evolution Explorer), and WISE (Wide-field Infrared Survey Explorer). We show that IRX generally correlates with stellar mass (M *), star formation rate, gas-phase metallicity (Z), infrared luminosity (L IR), and the half-light radius (R e). A weak correlation of IRX with axial ratio (b / a) is driven by the inclination and thus seen as a projection effect. By examining the tightness and the scatter of these correlations, we find that SFGs obey an empirical relation of the form IRX  =  |$10^\alpha \, (L_{\rm IR})^{\beta }\, R_{\rm e}^{-\gamma }\, (b/a)^{-\delta }$|⁠, where the power-law indices all increase with metallicity. The best-fitting relation yields a scatter of ∼0.17 dex and no dependence on stellar mass. Moreover, this empirical relation also holds for distant SFGs out to z  = 3 in a population-averaged sense, suggesting it to be universal over cosmic time. Our findings reveal that IRX approximately increases with |$L_{\rm IR}/R_{\rm e}^{[1.3 - 1.5]}$| instead of |$L_{\rm IR}/R_{\rm e}^{2}$| (i.e. surface density). We speculate this may be due to differences in the spatial extent of stars versus star formation and/or complex star-dust geometries. We conclude that not stellar mass but IR luminosity, metallicity, and galaxy size are the key parameters jointly determining dust obscuration in SFGs. [ABSTRACT FROM AUTHOR]

We present a cross-calibration of CO- and dust-based molecular gas masses at z ≤ 0.2. Our results are based on a survey with the IRAM 30-m telescope collecting CO(1–0) measurements of 78 massive (logM⋆/M⊙> 10) galaxies with known gas-phase metallicities and with IR photometric coverage from Wide-field Infrared Survey Explorer(WISE; 22 $\mu$ m) and Herschel Spectral and Photometric Imaging Receiver (SPIRE; 250, 350, 500 $\mu$ m). We find a tight relation (∼0.17 dex scatter) between the gas masses inferred from CO and dust continuum emission, with a minor systematic offset of 0.05 dex. The two methods can be brought into agreement by applying a metallicity-dependent adjustment factor (∼0.13 dex scatter). We illustrate that the observed offset is consistent with a scenario in which dust traces not only molecular gas but also part of the Hi reservoir, residing in the H2-dominated region of the galaxy. Observations of the CO(2–1) to CO(1–0) line ratio for two-thirds of the sample indicate a narrow range in excitation properties, with a median ratio of luminosities ⟨R21⟩ ∼ 0.64. Finally, we find dynamical mass constraints from spectral line profile fitting to agree well with the anticipated mass budget enclosed within an effective radius, once all mass components (stars, gas, and dark matter) are accounted for. [ABSTRACT FROM AUTHOR]

We performed a detailed study of the evolution of the star formation rate (SFR) and stellar mass of the brightest group galaxies (BGGs) and their relative contribution to the total baryon budget within R200 (fBGGb,200). The sample comprises 407 BGGs selected from X-ray groups (M200 = 1012.8-1014M☉) out to z ∼1.3 identified in the Cosmic Evolution Survey (COSMOS), XMM Large-Scale Structure survey (XMM-LSS), and the All-Wavelength Extended Groth strip International Survey (AEGIS) fields. We find that BGGs constitute two distinct populations of quiescent and star-forming galaxies and their mean SFR is ∼2 dex higher than the median SFR at z < 1.3. Both the mean and the median SFRs decline with time by >2 dex.We take into account the halo mass growth of groups in selecting the sample of BGGs and find that the mean (median) stellar mass of BGGs has grown by 0.3 dex since z = 1.3 to the present day. We show that up to ∼45 per cent of the stellar mass growth in a star-forming BGG can be due to its star formation activity.With respect to fBGGb,200, we find it to increase with decreasing redshift by ∼0.35 dex, while decreasing with halo mass in a redshift-dependent manner. We show that the slope of the relation between fBGGb,200 and halo mass increases negatively with decreasing redshift. This trend is driven by an insufficient star formation in BGGs, compared to the halo growth rate. We separately show the BGGs with the 20 per cent highest fBGGb,200 are generally non-star-forming galaxies and grow in mass by processes not related to star formation (e.g. dry mergers and tidal striping). We present the M-Mh and M/Mh-Mh relations and compare them with semi-analytic model predictions and a number of results from the literature.We quantify the intrinsic scatter in stellar mass of BGGs at fixed halo mass (σlogM ) and find that σlogM increases from 0.3 dex at z ∼0.2-0.5 dex at z ∼1.0 due to the bimodal distribution of stellar mass. [ABSTRACT FROM AUTHOR]