ABSTRACT
By compiling a comprehensive census of literature studies, we investigate the evolution of the main sequence (MS) of star-forming galaxies (SFGs) in the widest range of redshift (0 < z < 6) ...and stellar mass (108.5–1011.5 M⊙) ever probed. We convert all observations to a common calibration and find a remarkable consensus on the variation of the MS shape and normalization across cosmic time. The relation exhibits a curvature towards the high stellar masses at all redshifts. The best functional form is governed by two parameters: the evolution of the normalization and the turnover mass (M0(t)), which both evolve as a power law of the Universe age. The turn-over mass determines the MS shape. It marginally evolves with time, making the MS slightly steeper towards z ∼ 4–6. At stellar masses below M0(t), SFGs have a constant specific SFR (sSFR), while above M0(t) the sSFR is suppressed. We find that the MS is dominated by central galaxies. This allows to turn M0(t) into the corresponding host halo mass. This evolves as the halo mass threshold between cold and hot accretion regimes, as predicted by the theory of accretion, where the central galaxy is fed or starved of cold gas supply, respectively. We, thus, argue that the progressive MS bending as a function of the Universe age is caused by the lower availability of cold gas in haloes entering the hot accretion phase, in addition to black hole feedback. We also find qualitatively the same trend in the largest sample of star-forming galaxies provided by the IllustrisTNG simulation. Nevertheless, we still note large quantitative discrepancies with respect to observations, in particular at the high-mass end. These can not be easily ascribed to biases or systematics in the observed SFRs and the derived MS.
By using a set of different star formation rate (SFR) indicators, including Wide-field Infrared Survey Explorer (WISE) mid-infrared and H α emission, we study the slope of the main sequence (MS) of ...local star-forming galaxies at stellar masses larger than 10^{10} M_{⊙ }. The slope of the relation strongly depends on the SFR indicator used. In all cases, the local MS shows a bending at high stellar masses with respect to the slope obtained in the low-mass regime. While the distribution of galaxies in the upper envelope of the MS is consistent with a lognormal distribution, the lower envelope shows an excess of galaxies, which increases as a function of the stellar mass but varies as a function of the SFR indicator used. The scatter of the best lognormal distribution increases with stellar mass from ∼0.3 dex at 10^{10} M_{⊙ } to ∼0.45 at 10^{11} M_{⊙ }. The MS high-mass end is dominated by central galaxies of group-sized haloes with a red bulge and a disc redder than the lower mass counterparts. We argue that the MS bending in this region is due to two processes: (i) the formation of a bulge component as a consequence of the increased merger activity in groups, and (ii) the cold gas starvation induced by the hot halo environment, which cuts off the gas inflow on to the disc. Similarly, the increase of the MS scatter at high stellar masses would be explained by the larger spread of star formation histories of central group and cluster galaxies with respect to lower mass systems.
We study the efficiency of galactic feedback in the early Universe by stacking the C II 158
μ
m emission in a large sample of normal star-forming galaxies at 4 <
z
< 6 from the ALMA Large Program ...to INvestigate C II at Early times (ALPINE) survey. Searching for typical signatures of outflows in the high-velocity tails of the stacked C II profile, we observe (i) deviations from a single-component Gaussian model in the combined residuals and (ii) broad emission in the stacked C II spectrum, with velocities of |
v
|≲500 km s
−1
. The significance of these features increases when stacking the subset of galaxies with star formation rates (SFRs) higher than the median (SFR
med
= 25
M
⊙
yr
−1
), thus confirming their star-formation-driven nature. The estimated mass outflow rates are comparable to the SFRs, yielding mass-loading factors of the order of unity (similarly to local star-forming galaxies), suggesting that star-formation-driven feedback may play a lesser role in quenching galaxies at
z
> 4. From the stacking analysis of the datacubes, we find that the combined C II core emission (|
v
|< 200 km s
−1
) of the higher-SFR galaxies is extended on physical sizes of ∼30 kpc (diameter scale), well beyond the analogous C II core emission of lower-SFR galaxies and the stacked far-infrared continuum. The detection of such extended metal-enriched gas, likely tracing circumgalactic gas enriched by past outflows, corroborates previous similar studies, confirming that baryon cycle and gas exchanges with the circumgalactic medium are at work in normal star-forming galaxies already at early epochs.
ABSTRACT We investigate the physical conditions of ionized gas in high-z star-forming galaxies using diagnostic diagrams based on the rest-frame optical emission lines. The sample consists of 701 ...galaxies with an H detection at , from the Fiber Multi-Object Spectrograph (FMOS)-COSMOS survey, that represent the normal star-forming population over the stellar mass range , with those at being well sampled. We confirm an offset of the average location of star-forming galaxies in the Baldwin-Phillips-Terlevich (BPT) diagram ( versus ), primarily toward higher , compared with local galaxies. Based on the S ii ratio, we measure an electron density ( ), which is higher than that of local galaxies. Based on comparisons to theoretical models, we argue that changes in emission-line ratios, including the offset in the BPT diagram, are caused by a higher ionization parameter both at fixed stellar mass and at fixed metallicity, with additional contributions from a higher gas density and possibly a hardening of the ionizing radiation field. Ionization due to active galactic nuclei is ruled out as assessed with Chandra. As a consequence, we revisit the mass-metallicity relation using and a new calibration including as recently introduced by Dopita et al. Consistent with our previous results, the most massive galaxies ( ) are fully enriched, while those at lower masses have metallicities lower than local galaxies. Finally, we demonstrate that the stellar masses, metallicities, and star formation rates of the FMOS sample are well fit with a physically motivated model for the chemical evolution of star-forming galaxies.
Abstract
We present ALMA observations at 107.291 GHz (band 3) and 214.532 GHz (band 6) of GMASS 0953, a star-forming galaxy at z = 2.226 hosting an obscured active galactic nucleus (AGN) that has ...been proposed as a progenitor of compact quiescent galaxies (QGs). We measure for the first time the size of the dust and molecular gas emission of GMASS 0953 that we find to be extremely compact (∼1 kpc). This result, coupled with a very high interstellar medium (ISM) density (n ∼ 105.5 cm−3), a low gas mass fraction (∼0.2), and a short gas depletion time-scale (∼150 Myr), implies that GMASS 0953 is experiencing an episode of intense star formation in its central region that will rapidly exhaust its gas reservoirs, likely aided by AGN-induced feedback, confirming its fate as a compact QG. Kinematic analysis of the CO(6–5) line shows evidence of rapidly rotating gas (Vrot = 320$^{+92}_{-53}$ km s−1), as observed also in a handful of similar sources at the same redshift. On-going quenching mechanisms could either destroy the rotation or leave it intact leading the galaxy to evolve into a rotating QG.
ABSTRACT
In this work, we analyse the connection between gas availability and the position of a region with respect to the spatially resolved main-sequence (MS) relation. Following the procedure ...presented in Enia et al. (2020), for a sample of five face-on, grand design spiral galaxies located on the MS we obtain estimates of stellar mass and star formation rate surface densities (Σ⋆ and ΣSFR) within cells of 500 pc size. Thanks to H i 21cm and 12CO(2–1) maps of comparable resolution, within the same cells we estimate the surface densities of the atomic (ΣH i) and molecular ($\Sigma _{\rm {H_2}}$) gas and explore the correlations among all these quantities. Σ⋆, ΣSFR, and $\Sigma _{\rm {H_2}}$ define a 3D relation whose projections are the spatially resolved MS, the Kennicutt–Schmidt law and the molecular gas MS. We find that $\Sigma _{\rm {H_2}}$ steadily increases along the MS relation and is almost constant perpendicular to it. ΣH i is nearly constant along the MS and increases in its upper envelope. As a result, ΣSFR can be expressed as a function of Σ⋆ and ΣH i, following the relation log ΣSFR = 0.97log Σ⋆ + 1.99log ΣH i − 11.11. We show that the total gas fraction significantly increases towards the starburst regions, accompanied by a weak increase in star formation efficiency. Finally, we find that H2/H i varies strongly with the distance from the MS, dropping dramatically in regions of intense star formation, where the UV radiation from newly formed stars dissociates the H2 molecule, illustrating the self-regulating nature of the star formation process.
We investigate the star formation properties of ∼800 sources detected in one of the deepest radio surveys at 1.4 GHz. Our sample spans a wide redshift range (∼0.1–4) and about four orders of ...magnitude in star formation rate (SFR). It includes both star-forming galaxies (SFGs) and active galactic nuclei (AGNs), further divided into radio-quiet (RQ) and radio-loud objects. We compare the SFR derived from the far-infrared luminosity, as traced by Herschel, with the SFR computed from their radio emission. We find that the radio power is a good SFR tracer not only for pure SFGs but also in the host galaxies of RQ AGNs, with no significant deviation with redshift or specific SFR. Moreover, we quantify the contribution of the starburst activity in the SFG population and the occurrence of AGNs in sources with different level of star formation. Finally, we discuss the possibility of using deep radio survey as a tool to study the cosmic star formation history.
We present a complete census of all Herschel-detected sources within the six massive lensing clusters of the HST Frontier Fields (HFF). We provide a robust legacy catalogue of 263 sources with ...Herschel fluxes, primarily based on imaging from the Herschel Lensing Survey and PEP/HerMES Key Programmes. We optimally combine Herschel, Spitzer and WISE infrared (IR) photometry with data from HST, VLA and ground-based observatories, identifying counterparts to gain source redshifts. For each Herschel-detected source we also present magnification factor (μ), intrinsic IR luminosity and characteristic dust temperature, providing a comprehensive view of dust-obscured star formation within the HFF. We demonstrate the utility of our catalogues through an exploratory overview of the magnified population, including more than 20 background sub-LIRGs unreachable by Herschel without the assistance gravitational lensing.
ABSTRACT
By using the deepest available mid- and far-infrared surveys in the CANDELS, GOODS, and COSMOS fields we study the evolution of the main sequence (MS) of star-forming galaxies (SFGs) from z ...∼ 0 to ∼ 2.5 at stellar masses larger than 1010 M⊙. The MS slope and scatter are consistent with a rescaled version of the local relation and distribution, shifted at higher values of star formation rate (SFR) according to ∝ (1 + $z$)3.2. The relation exhibits a bending at the high-mass end and a slightly increasing scatter as a function of the stellar mass. We show that the previously reported evolution of the MS slope, in the considered mass and redshift range, is due to a selection effect. The distribution of galaxies in the MS region at fixed stellar mass is well represented by a single lognormal distribution at all redshifts and masses, with starburst galaxies occupying the tail at high SFR.
ABSTRACT
We analyse the spatially resolved relation between stellar mass (M⋆) and star formation rate (SFR) in disc galaxies (i.e. the main sequence, MS). The studied sample includes eight nearby ...face-on grand-design spirals, e.g. the descendant of high-redshift, rotationally supported star-forming galaxies. We exploit photometric information over 23 bands, from the UV to the far-IR, from the publicly available DustPedia data base to build spatially resolved maps of stellar mass and SFRs on sub-galactic scales of 0.5–1.5 kpc, by performing a spectral energy distribution fitting procedure that accounts for both the observed and obscured star formation processes, over a wide range of internal galaxy environments (bulges, spiral arms, and outskirts). With more than 30 000 physical cells, we have derived a definition of the local spatially resolved MS per unit area for discs, log (ΣSFR) = 0.82log (Σ*) − 8.69. This is consistent with the bulk of recent results based on optical IFU, using the H α line emission as an SFR tracer. Our work extends the analysis at lower sensitivities in both M⋆ and SFR surface densities, up to a factor of ∼10. The self-consistency of the MS relation over different spatial scales, from sub-galactic to galactic, as well as with a rescaled correlation obtained for high-redshift galaxies, clearly proves its universality.
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![The ALPINE-ALMA [C II] surv...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-6361/small "The ALPINE-ALMA [C II] survey: Star-formation-driven outflows and circumgalactic enrichment in the early Universe")
