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The evolution of the dust grain size distribution has been studied in recent years with great detail in cosmological hydrodynamical simulations taking into account all the channels under which dust evolves in the interstellar medium. We present a systematic analysis of the observed spectral energy distribution of a large sample of galaxies in the local Universe in order to derive not only the total dust masses but also the relative mass fraction between small and large dust grains (DS / DL). Simulations reproduce fairly well the observations except for the high-stellar mass regime where dust masses tend to be overestimated. We find that ∼45 per cent of galaxies exhibit DS / DL consistent with the expectations of simulations, while there is a subsample of massive galaxies presenting high DS / DL (log (DS / DL) ∼ −0.5), and deviating from the prediction in simulations. For these galaxies which also have high-molecular gas mass fractions and metallicities, coagulation is not an important mechanism affecting the dust evolution. Including diffusion, transporting large grains from dense regions to a more diffuse medium where they can be easily shattered, would explain the observed high DS / DL values in these galaxies. With this study, we reinforce the use of the small-to-large grain mass ratio to study the relative importance of the different mechanisms in the dust life cycle. Multiphase hydrodynamical simulations with detailed feedback prescriptions and more realistic subgrid models for the dense phase could help to reproduce the evolution of the dust grain size distribution traced by observations. [ABSTRACT FROM AUTHOR]

We present Herschel –PACS spectroscopy of four main-sequence star-forming galaxies at z ∼ 1.5. We detect [OI]63  μ m line emission in BzK-21000 at z  = 1.5213, and measure a line luminosity, |$L_{\rm [O\, {\small I}]63\, \mu m} = (3.9\pm 0.7)\times 10^9$|  L⊙. Our PDR modelling of the interstellar medium in BzK-21000 suggests a UV radiation field strength, G ∼ 320 G 0, and gas density, n ∼ 1800 cm−3, consistent with previous LVG modelling of the molecular CO line excitation. The other three targets in our sample are individually undetected in these data, and we perform a spectral stacking analysis which yields a detection of their average emission and an [O  i ]63  μ m line luminosity, |$L_{\rm [O\, {\small I}]63\, \mu m} = (1.1\pm 0.2)\times 10^9$|  L⊙. We find that the implied luminosity ratio, |$L_{\rm [O\, {\small I}]63\, \mu m}/L_{\rm IR}$|⁠ , of the undetected BzK-selected star-forming galaxies broadly agrees with that of low-redshift star-forming galaxies, while BzK-21000 has a similar ratio to that of a dusty star-forming galaxy at z ∼ 6. The high [O  i ]63  μ m line luminosities observed in BzK-21000 and the z ∼ 1−3 dusty and sub-mm luminous star-forming galaxies may be associated with extended reservoirs of low density, cool neutral gas. [ABSTRACT FROM AUTHOR]

We present an analysis of the dust attenuation of star-forming galaxies at z  = 2.5–4.0 through the relationship between the UV spectral slope (β), stellar mass (M *), and the infrared excess (IRX = L IR/ L UV) based on far-infrared continuum observations from the Atacama Large Millimeter/sub-millimeter Array (ALMA). Our study exploits the full ALMA archive over the COSMOS field processed by the A3COSMOS team, which includes an unprecedented sample of ∼1500 galaxies at z ∼ 3 as primary or secondary targets in ALMA band 6 or 7 observations with a median continuum sensitivity of 126 |$\rm {\mu Jy\, beam}^{-1}$| (1σ). The detection rate is highly mass dependent, decreasing drastically below log (M */M⊙) = 10.5. The detected galaxies show that the IRX–β relationship of massive (log  M */M⊙ > 10) main-sequence galaxies at z  = 2.5–4.0 is consistent with that of local galaxies, while starbursts are generally offset by |$\sim 0.5\, {\rm dex}$| to larger IRX values. At the low-mass end, we derive upper limits on the infrared luminosities through stacking of the ALMA data. The combined IRX– M * relation at |$\rm {log\, ({\it M}_{\ast }/\mathrm{M}_{\odot })\gt 9}$| exhibits a significantly steeper slope than reported in previous studies at similar redshifts, implying little dust obscuration at log  M */M⊙ < 10. However, our results are consistent with earlier measurements at z ∼ 5.5, indicating a potential redshift evolution between z ∼ 2 and z ∼ 6. Deeper observations targeting low-mass galaxies will be required to confirm this finding. [ABSTRACT FROM AUTHOR]

We investigate the fraction of close pairs and morphologically identified mergers on and above the star-forming main sequence (MS) at 0.2 ≤  z  ≤2.0. The novelty of our work lies in the use of a non-parametric morphological classification performed on resolved stellar mass maps, reducing the contamination by non-interacting, high-redshift clumpy galaxies. We find that the merger fraction rapidly rises to ≥70 per cent above the MS, implying that – already at z ≳ 1 – starburst (SB) events (ΔMS ≥ 0.6) are almost always associated with a major merger (1:1 to 1:6 mass ratio). The majority of interacting galaxies in the SB region are morphologically disturbed, late-stage mergers. Pair fractions show little dependence on MS offset and pairs are more prevalent than late-stage mergers only in the lower half of the MS. In our sample, major mergers on the MS occur with a roughly equal frequency of ∼5–10 per cent at all masses ≳ 1010  M ⊙. The MS major merger fraction roughly doubles between z = 0.2 and 2, with morphological mergers driving the overall increase at z ≳ 1. The differential redshift evolution of interacting pairs and morphologically classified mergers on the MS can be reconciled by evolving observability time-scales for both pairs and morphological disturbances. The observed variation of the late-stage merger fraction with ΔMS follows the perturbative 2-Star Formation Mode model, where any MS galaxy can experience a continuum of different star formation rate enhancements. This points to an SB–merger connection not only for extreme events, but also more moderate bursts which merely scatter galaxies upward within the MS, rather than fully elevating them above it. [ABSTRACT FROM AUTHOR]

We study a population of significantly sub-solar enrichment galaxies at z  = 1.99, to investigate how molecular gas, dust, and star formation relate in low-metallicity galaxies at the peak epoch of star formation. We target our sample with several deep Atacama Large Millimeter/submillimeter Array and Very Large Array datasets, and find no individual detections of CO[4–3], CO[1–0], or dust, in stark contrast to the  >60 per cent detection rate expected for solar-enrichment galaxies with these MS H α star formation rates (SFRs). We find that both low- and high-density molecular gas (traced by CO[1–0] and CO[4–3], respectively) are affected by the low enrichment, showing sample average (stacked) luminosity deficits >0.5–0.7 dex below expectations. This is particularly pertinent for the use of high-J CO emission as a proxy of instantaneous SFR. Our individual galaxy data and stacked constraints point to a strong inverse dependence ∝  Z γ of gas-to-dust ratios (G/D) and CO-to-H2 conversion factors (αCO) on metallicity at z  ∼ 2, with γG/D <−2.2 and |$\gamma _{\alpha _{\rm CO}}\lt $| −0.8, respectively. We quantify the importance of comparing G/D and αCO versus metallicity trends from the literature on a common, suitably normalized metallicity scale. When accounting for systematic offsets between different metallicity scales, our z  ∼ 2 constraints on these scaling relations are consistent with the corresponding relations for local galaxies. However, among those local relations, we favour those with a steep/double power-law dependence of G/D on metallicity. Finally, we discuss the implications of these findings for (a) gas mass measurements for sub- M * galaxies, and (b) efforts to identify the characteristic galaxy mass scale contributing most to the comoving molecular gas density at z  = 2. [ABSTRACT FROM AUTHOR]

Exploring how radio-emitting active galactic nuclei (AGNs) behave and evolve with time is critical for understanding how AGN feedback impacts galaxy evolution. In this work, we investigate the relationship between 1.4 GHz radio continuum AGN luminosity (⁠|$L^{\rm AGN}_{\rm 1.4}$|⁠), specific black hole accretion rate (s-BHAR, defined as the accretion luminosity relative to the galaxy stellar mass), and redshift, for a luminosity-complete sample of radio-selected AGNs in the VLA COSMOS 3 GHz Large Project. The sample was originally selected from radio-continuum observations at 3 GHz, and includes about 1800 radio AGNs identified via (>2 σ) radio-excess relative to the infrared-radio correlation of star-forming galaxies. We further select a subsample of over 1200 radio AGNs that is complete in |$L^{\rm AGN}_{\rm 1.4}$| over different redshift ranges, out to |$z$| ∼ 4, and use X-ray stacking to calculate the average s-BHAR in each |$L^{\rm AGN}_{\rm 1.4}$| – |$z$| bin. We find that the average s-BHAR is independent of |$L^{\rm AGN}_{\rm 1.4}$|⁠, at all redshifts. However, we see a strong increase of s-BHAR with redshift, at fixed |$L^{\rm AGN}_{\rm 1.4}$|⁠. This trend resembles the strong increase in the fraction of star-forming host galaxies [based on the (NUV − r)/(r − J) colours] with redshift, at fixed |$L^{\rm AGN}_{\rm 1.4}$|⁠. A possible explanation for this similarity might imply a link between average AGN radiative power and availability of cold gas supply within the host galaxy. This study corroborates the idea that radio-selected AGNs become more radiatively efficient towards earlier epochs, independently of their radio power. [ABSTRACT FROM AUTHOR]

We present ALMA Band 9 observations of the [C ii ]158 |$\mu$| m emission for a sample of 10 main-sequence galaxies at redshift |$z$| ∼ 2, with typical stellar masses (log M ⋆/M⊙∼ 10.0–10.9) and star formation rates (∼35–115 M⊙yr−1). Given the strong and well-understood evolution of the interstellar medium from the present to |$z$| = 2, we investigate the behaviour of the [C ii ] emission and empirically identify its primary driver. We detect [C ii ] from six galaxies (four secure and two tentative) and estimate ensemble averages including non-detections. The [C ii ]-to-infrared luminosity ratio (⁠|${\rm [C\, {\small II}]}$| / L IR) of our sample is similar to that of local main-sequence galaxies (∼2 × 10−3), and ∼10 times higher than that of starbursts. The [C ii ] emission has an average spatial extent of 4–7 kpc, consistent with the optical size. Complementing our sample with literature data, we find that the [C ii ] luminosity correlates with galaxies' molecular gas mass, with a mean absolute deviation of 0.2 dex and without evident systematics: the [C ii ]-to-H2conversion factor (⁠|$\alpha _{\rm [C\, {\small II}]} \sim 30$| M⊙/L⊙) is largely independent of galaxies' depletion time, metallicity, and redshift. [C ii ] seems therefore a convenient tracer to estimate galaxies' molecular gas content regardless of their starburst or main-sequence nature, and extending to metal-poor galaxies at low and high redshifts. The dearth of [C ii ] emission reported for |$z$| > 6–7 galaxies might suggest either a high star formation efficiency or a small fraction of ultraviolet light from star formation reprocessed by dust. [ABSTRACT FROM AUTHOR]

We present results on the dust attenuation of galaxies at redshift ∼3-6 by studying the relationship between the UV spectral slope (βUV) and the infrared excess (IRX; LIR/LUV) using Atacama Large Millimeter/submillimeter Array (ALMA) far-infrared continuum observations. Our study is based on a sample of 67 massive, star-forming galaxies with a median mass of M∼ ∼ 1010.7 M☉ spanning a redshift range z = 2.6-3.7 (median z = 3.2) that were observed with ALMA at λrest = 300 μm. Both the individual ALMA detections (41 sources) and stacks including all galaxies show the IRX-βUV relationship at z ∼ 3 is mostly consistent with that of local starburst galaxies on average. However, we find evidence for a large dispersion around the mean relationship by up to ±0.5 dex. Nevertheless, the locally calibrated dust correction factors based on the IRX-βUV relation are on average applicable to main-sequence z ∼ 3 galaxies. This does not appear to be the case at even higher redshifts, however. Using public ALMA observations of z ∼ 4-6 galaxies we find evidence for a significant evolution in the IRX-βUV and the IRX-M* relations beyond z ∼ 3 towards lower IRX values. We discuss several caveats that could affect these results, including the assumed dust temperature. ALMA observations of larger z > 3 galaxy sample spanning a wide range of physical parameters (e.g. lower stellar mass) will be important to investigate this intriguing redshift evolution further. [ABSTRACT FROM AUTHOR]

We present deep ALMA CO(5-4) observations of a main-sequence, clumpy galaxy at z = 1.5 in the HUDF. Thanks to the ∼0″.5 resolution of the ALMA data, we can link stellar population properties to the CO(5-4) emission on scales of a few kiloparsec. We detect strong CO(5-4) emission from the nuclear region of the galaxy, consistent with the observed LIR-L'CO(5-4) correlation and indicating ongoing nuclear star formation. The CO(5-4) gas component appears more concentrated than other star formation tracers or the dust distribution in this galaxy. We discuss possible implications of this difference in terms of star formation efficiency and mass build-up at the galaxy centre. Conversely, we do not detect any CO(5-4) emission from the UV-bright clumps. This might imply that clumps have a high star formation efficiency (although they do not display unusually high specific star formation rates) and are not entirely gas dominated, with gas fractions no larger than that of their host galaxy (∼50 per cent). Stellar feedback and disc instability torques funnelling gas towards the galaxy centre could contribute to the relatively low gas content. Alternatively, clumps could fall in a more standard star formation efficiency regime if their actual star formation rates are lower than generally assumed. We find that clump star formation rates derived with several different, plausible methods can vary by up to an order of magnitude. The lowest estimates would be compatible with a CO(5-4) non-detection even for main-sequence like values of star formation efficiency and gas content. [ABSTRACT FROM AUTHOR]

Similarly to the cosmic star formation history, the black hole accretion rate density of the Universe peaked at 1CO ∼ 6.3-25.1 × 109 L⊚, which translates to a molecular hydrogen gas mass of 2.5–10 × 1010M⊚ assuming conventional conversion factor of αCO ∼ 3.6. Our results indicate a >99 per cent probability of lower depletion time-scales and lower molecular gas fractions in AGN hosts with respect to the non-AGN comparison sample. We discuss the implications of these observations on the impact that AGN feedback may have on star formation efficiency of z >1 galaxies. [ABSTRACT FROM AUTHOR]

HE0450-2958, an interacting quasar-starburst galaxy pair at z = 0.285, is one of the best- known examples of strong star formation activity in the presence of a quasar-driven jet. We present new multiband Karl G. Jansky Very Large Array-imaging covering 1-6 GHz and reaching an angular resolution of up to 0.6 arcsec (a sixfold improvement over existing radio data). We confirm the previous detection of a spatially extended radio component around the quasar, indicating that there is ongoing star formation activity in the quasar host galaxy. For the first time, we directly detect a jet-like bipolar outflow from the quasar aligned with its companion star-forming galaxy (SFG) and several blobs of ionized gas in its vicinity identified in previous studies. Within the companion SFG, we find evidence for a flattening of the synchrotron spectral index towards the point of intersection with the jet axis, further suggesting that the outflow may actually be impacting its interstellar medium. We discuss two possible mechanisms that could have triggered the starburst in the companion SFG: a wet-dry merger with the quasar and jet-induced star formation. While triggering through interaction-driven gas dynamics cannot be excluded with current data, our new observations make HE0450-2958 a strong candidate for jet-induced star formation, and one of the rare links between local systems (like Minkowski's Object or Centaurus A) and the high-z regime where radio-optical alignments suggest that this phenomenon could be more common. [ABSTRACT FROM AUTHOR]

We investigate the evolution of the galaxy star formation rate function (SFRF) and cosmic star formation rate density (CSFRD) of z ~ 1-4 galaxies, using cosmological smoothed particle hydrodynamic (SPH) simulations and a compilation of ultraviolet (UV), infrared (IR) and Ha observations. These tracers represent different populations of galaxies with the IR light being a probe of objects with high star formation rates and dust contents, while UV and Ha observations provide a census of low star formation galaxies where mild obscuration occurs. We compare the above SFRFs with the results of SPH simulations run with the code P-GADGET3(XXL). We focus on the role of feedback from active galactic nuclei (AGN) and supernovae in form of galactic winds. The AGN feedback prescription that we use decreases the simulated CSFRD at z < 3 but is not sufficient to reproduce the observed evolution at higher redshifts. We explore different wind models and find that the key factor for reproducing the evolution of the observed SFRF and CSFRD at z ~ 1-4 is the presence of a feedback prescription that is prominent at high redshifts (z = 4) and becomes less efficient with time. We show that variable galactic winds which are efficient at decreasing the SFRs of low-mass objects are quite successful in reproducing the observables. [ABSTRACT FROM AUTHOR]

We have developed a new prior-based source extraction tool, XID+, to carry out photometry in the Herschel SPIRE (Spectral and Photometric Imaging Receiver) maps at the positions of known sources. XID+ is developed using a probabilistic Bayesian framework that provides a natural framework in which to include prior information, and uses the Bayesian inference tool Stan to obtain the full posterior probability distribution on flux estimates. In this paper, we discuss the details of XID+ and demonstrate the basic capabilities and performance by running it on simulated SPIRE maps resembling the COSMOS field, and comparing to the current prior-based source extraction tool DESPHOT. Not only we show that XID+ performs better on metrics such as flux accuracy and flux uncertainty accuracy, but we also illustrate how obtaining the posterior probability distribution can help overcome some of the issues inherent with maximum-likelihood-based source extraction routines. We run XID+ on the COSMOS SPIRE maps from Herschel Multi-Tiered Extragalactic Survey using a 24-µm catalogue as a positional prior, and a uniform flux prior ranging from 0.01 to 1000 mJy. We show the marginalized SPIRE colour--colour plot and marginalized contribution to the cosmic infrared background at the SPIRE wavelengths. XID+ is a core tool arising from the Herschel Extragalactic Legacy Project (HELP) and we discuss how additional work within HELP providing prior information on fluxes can and will be utilized. The software is available at https://github.com/H-E-L-P/XID_plus.We also provide the data product for COSMOS. We believe this is the first time that the full posterior probability of galaxy photometry has been provided as a data product. [ABSTRACT FROM AUTHOR]

The Herschel Extragalactic Legacy Project (HELP) brings together a vast range of data from many astronomical observatories. Its main focus is on the Herschel data, which maps dustobscured star formation over 1300 deg². With this unprecedented combination of data sets, it is possible to investigate how the star formation versus stellar mass relation (main sequence) of star-forming galaxies depends on environment. In this pilot study, we explore this question within 0.1 2. We also estimate the evolution of the star formation rate density in the COSMOS field, and our results are consistent with previous measurements at z < 1.5 and z > 2 but we find a 1.4+0.3-0.2 times higher peak value of the star formation rate density at z ~ 1.9. [ABSTRACT FROM AUTHOR]

Using a phenomenological approach, we self-consistently model the redshift evolution of the ultraviolet (UV) and infrared (IR) luminosity functions across cosmic time, as well as a range of observed IR properties of UV-selected galaxy population. This model is an extension of the 2SFM (2 star formation modes) formalism, which is based on the observed ‘main sequence’ of star-forming galaxies, i.e. a strong correlation between their stellar mass and their star formation rate, and a secondary population of starbursts with an excess of star formation. The balance between the UV light from young, massive stars and the dust-reprocessed IR emission is modelled following the empirical relation between the attenuation (IRX for IR excess hereafter) and the stellar mass, assuming a scatter of 0.4 dex around this relation. We obtain good overall agreement with the measurements of the IR luminosity function up to z ∼ 3 and the UV luminosity functions up to z ∼ 6, and show that a scatter on the IRX–M relation is mandatory to reproduce these observables. We also naturally reproduce the observed, flat relation between the mean IRX and the UV luminosity at LUV > 109.5 L⊙. Finally, we perform predictions of the UV properties and detectability of IR-selected samples and the vice versa, and discuss the results in the context of the UV-rest-frame and sub-millimetre surveys of the next decade. [ABSTRACT FROM AUTHOR]

We present detections of the CO(J = 1–0) emission line in a sample of four massive star-forming galaxies at z ∼ 1.5–2.2 obtained with the Karl G. Jansky Very Large Array. Combining these observations with previous CO(2–1) and CO(3–2) detections of these galaxies, we study the excitation properties of the molecular gas in our sample sources. We find an average line brightness temperature ratios of R21 = 0.70 ± 0.16 and R31 = 0.50 ± 0.29, based on measurements for three and two galaxies, respectively. These results provide additional support to previous indications of sub-thermal gas excitation for the CO(3–2) line with a typically assumed line ratio R31 ∼ 0.5. For one of our targets, BzK-21000, we present spatially resolved CO line maps. At the resolution of 0.18 arcsec (1.5 kpc), most of the emission is resolved out except for some clumpy structure. From this, we attempt to identify molecular gas clumps in the data cube, finding four possible candidates. We estimate that <40 per cent of the molecular gas is confined to giant clumps (∼1.5 kpc in size), and thus most of the gas could be distributed in small fainter clouds or in fairly diffuse extended regions of lower brightness temperatures than our sensitivity limit. [ABSTRACT FROM AUTHOR]

The β2-integrin Family of adhesion molecules and their ligands. The ICAM molecules, probably have an important role to play in the intestinal immune response. To date, any data published regarding the intestinal expression or β2-integrins and ICAMs have mostly described only mucosal expression. The presence in the intestine of αd, a newly described β2-integrin molecule has not yet been determined. To understand further the expression of these molecules in all layers of the intestine, a comprehensive study was undertaken in both normal colon and normal small intestine specimens from 15 patients (colon n = 15. and ileum n = 6) who underwent surgical resections. Immunohistochemistry was performed for CD18, CD11a. CD11 b. CD11c. αd. ICAM-1, ICAM-2. and ICAM-3. The colon and small intestine cases were grouped separately and each of the mucosal, submucosal, muscle and adventitial layers were scored for expression. The β2-integrin molecules were expressed by mononuclear cells in all layers of the bowel, predominantly in the mucosa and adventitia. CD11a showed the greatest mucosal expression and CD11b showed the greatest adventitial expression, αd exhibited expression in all bowel layers, as well, with most intense expression in the mucosa and adventitia. CD11c exhibited the least expression of all α subunit molecules. The expression of these α-chains at times appeared to be greater than that seen for CD18 (β2), raising the possibility of non-β2-containing complexes (i.e. α-chains associating with an alternate β-chain). ICAM-l was expressed on endotheiium, particularly in the mucosa and rarely on mucosal mononuclear cells. ICAM-2 was predominantly on subtiuicosal endothelium and rarely expressed in colon mucosa and never expressed in ileal mucosa. ICAM-3 was expressed by mononuclear cells throughout the bowel wall, but also on adventitial endothelium in selected eases. In summary, we are reporting a comprehensive immunohistochemical study of the differential expression of β2-integrins, including the newly described αd molecule and the ICAM molecules in all layers of normal human colon and ileum. We raise the possibility that a second β2-integrin 3 subunit may exist, and we report that lCAM-3 is expressed on endothelium particularly in the adventitial layer. [ABSTRACT FROM AUTHOR]

Presents a study which demonstrates the occurrence of tandem repeat polymorphism and heteroplasmy in three species of redfish (Sebastes) in the northwest Atlantic Ocean. Materials and methods used to conduct this study; Information on tandem arrays in mitochondrial deoxyribonucleic acid (DNA); Population and interspecific characterization of tandem repeats and heteroplasmy; Discussion of the study.