Open accessJournal Article

# An ALMA survey of the S2CLS UDS field: optically invisible submillimetre galaxies

02 Mar 2021-Monthly Notices of the Royal Astronomical Society (Oxford Academic)-Vol. 502, Iss: 3, pp 3426-3435
Abstract: We analyse a robust sample of 30 near-infrared-faint (KAB > 25.3, 5σ) submillimetre galaxies (SMGs) selected from a 0.96 deg2 field to investigate their properties and the cause of their faintness in optical/near-infrared wavebands. Our analysis exploits precise identifications based on Atacama Large Millimeter Array (ALMA) 870-μm continuum imaging, combined with very deep near-infrared imaging from the UKIDSS Ultra Deep Survey. We estimate that SMGs with KAB > 25.3 mag represent 15 ± 2 per cent of the total population brighter than S870 = 3.6 mJy, with a potential surface density of ∼450 deg−2 above S870 ≥ 1 mJy. As such, they pose a source of contamination in surveys for both high-redshift ‘quiescent’ galaxies and very high redshift Lyman-break galaxies. We show that these K-faint SMGs represent the tail of the broader submillimetre population, with comparable dust and stellar masses to KAB ≤ 25.3 mag SMGs, but lying at significantly higher redshifts (z = 3.44 ± 0.06 versus z = 2.36 ± 0.11) and having higher dust attenuation (AV = 5.2 ± 0.3 versus AV = 2.9 ± 0.1). We investigate the origin of the strong dust attenuation and find indications that these K-faint galaxies have smaller dust continuum sizes than the KAB ≤ 25.3 mag galaxies, as measured by ALMA, which suggests their high attenuation is related to their compact sizes. We identify a correlation of dust attenuation with star formation rate surface density (SFR), with the K-faint SMGs representing the higher SFR and highest AV galaxies. The concentrated, intense star formation activity in these systems is likely to be associated with the formation of spheroids in compact galaxies at high redshifts, but as a result of their high obscuration these galaxies are completely missed in ultraviolet, optical, and even near-infrared surveys.

Topics: Galaxy (53%), Population (51%)
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Abstract: We study the impact of different galaxy statistics and empirical metallicity scaling relations on the merging rates and on the properties of compact objects binaries. First, we analyze the similarities and differences of using the star formation rate functions or the stellar mass functions as galaxy statistics for the computation of the cosmic star formation rate density. Then we investigate the effects of adopting the Fundamental Metallicity Relation or a classic Mass Metallicity Relation to assign metallicity to galaxies with given properties. We find that when the Fundamental Metallicity Relation is exploited, the bulk of the star formation occurs at relatively high metallicities even at high redshift; the opposite holds when the Mass Metallicity Relation is employed, since in this case the metallicity at which most of the star formation takes place strongly decreases with redshift. We discuss the various reasons and possible biases originating this discrepancy. Finally, we show the impact that these different astrophysical prescriptions have on the merging rates and on the properties of compact objects binaries; specifically, we present results for the redshift dependent merging rates and for the chirp mass and time delay distributions of the merging binaries.

Topics: Metallicity (59%), Star formation (58%), Stellar mass (55%) ... show more

16 Citations

Open accessJournal Article
U. Dudzevičiūtė1, Ian Smail1, A. M. Swinbank1, Chen-Fatt Lim2  +23 moreInstitutions (17)
Abstract: We analyse the physical properties of 121 SNR ≥ 5 sub-millimetre galaxies (SMGs) from the STUDIES 450 μm survey. We model their UV-to-radio spectral energy distributions using MAGPHYS+photo-z and compare the results to similar modelling of 850 μm-selected SMG sample from AS2UDS, to understand the fundamental physical differences between the two populations at the observed depths. The redshift distribution of the 450-μm sample has a median of z = 1.85 ± 0.12 and can be described by strong evolution of the far-infrared luminosity function. The fainter 450-μm sample has ∼14 times higher space density than the brighter 850-μm sample at z ≲ 2, and a comparable space density at z = 2–3, before rapidly declining, suggesting LIRGs are the main obscured population at z ∼ 1–2, while ULIRGs dominate at higher redshifts. We construct rest-frame ∼180-μm-selected and dust-mass-matched samples at z = 1–2 and z = 3–4 from the 450 and 850-μm samples, respectively, to probe the evolution of a uniform sample of galaxies spanning the cosmic noon era. Using far-infrared luminosity, dust masses, and an optically thick dust model, we suggest that higher redshift sources have higher dust densities due to inferred dust continuum sizes which are roughly half of those for the lower redshift population at a given dust mass, leading to higher dust attenuation. We track the evolution in the cosmic dust mass density and suggest that the dust content of galaxies is governed by a combination of both the variation of gas content and dust destruction time-scale.

11 Citations

Open accessJournal Article
Abstract: We report the discovery of a 10 comoving Mpc-scale structure traced by massive submillimeter galaxies (SMGs) at z~4.6. These galaxies are selected from an emission line search of ALMA Band 7 observations targeting 184 luminous submillimeter sources ($S_{850\mu{\rm m}}\geq$ 6.2 mJy) across 1.6 degrees$^2$ in the COSMOS field. We identify four [CII] emitting SMGs and two probable [CII] emitting SMG candidates at z=4.60-4.64 with velocity-integrated signal-to-noise ratio of SNR>8. Four of the six emitters are near-infrared blank SMGs. After excluding one SMG whose emission line is falling at the edge of the spectral window, all galaxies show clear velocity gradients along the major axes that are consistent with rotating gas disks. The estimated rotation velocities of the disks are 330-550 km s$^{-1}$ and the inferred host dark-matter halo masses are ~2-8 $\times$ 10$^{12}$M$_{\odot}$. From their estimated halo masses and [CII] luminosity function, we suggest that these galaxies have a high (50-100%) duty cycle and high (~0.1) baryon conversion efficiency (SFR relative to baryon accretion rate), and that they contribute $\simeq$2% to the total star-formation rate density at z=4.6. These SMGs are concentrated within just 0.3% of the full survey volume, suggesting they are strongly clustered. The extent of this structure and the individual halo masses suggest that these SMGs will likely evolve into members of a ~10$^{15}$M$_{\odot}$ cluster at z=0. This survey reveals synchronized dusty starburst in massive halos at z>4, which could be driven by mergers or fed by smooth gas accretion.

Topics: Galaxy (52%),

4 Citations

Open accessJournal Article
Rachel Cochrane1, P. N. Best, Ian Smail2, Edo Ibar3  +6 moreInstitutions (6)
Abstract: We present ~0.15'' spatial resolution imaging of SHiZELS-14, a massive (M*~10^11 M_sol), dusty, star-forming galaxy at z=2.24. Our rest-frame ~1kpc-scale, matched-resolution data comprise four different widely used tracers of star formation: the H-alpha emission line (from SINFONI/VLT), rest-frame UV continuum (from HST F606W imaging), the rest-frame far-infrared (from ALMA), and the radio continuum (from JVLA). Although originally identified by its modest H-alpha emission line flux, SHiZELS-14 appears to be a vigorously star-forming (SFR~1000 M_sol/yr) example of a submillimeter galaxy, probably undergoing a merger. SHiZELS-14 displays a compact, dusty central starburst, as well as extended emission in $\rm{H}\alpha$ and the rest-frame optical and FIR. The UV emission is spatially offset from the peak of the dust continuum emission, and appears to trace holes in the dust distribution. We find that the dust attenuation varies across the spatial extent of the galaxy, reaching a peak of at least A_H-alpha~5 in the most dusty regions, although the extinction in the central starburst is likely to be much higher. Global star-formation rates inferred using standard calibrations for the different tracers vary from ~10-1000 M_sol/yr, and are particularly discrepant in the galaxy's dusty centre. This galaxy highlights the biased view of the evolution of star-forming galaxies provided by shorter wavelength data.

3 Citations

Open accessJournal Article
Lorenzo Zanisi1, Francesco Shankar1, H. Fu1, Aldo Rodríguez-Puebla2  +13 moreInstitutions (12)
Abstract: The mean size (effective radius Re) of massive galaxies (MGs; Mstar > 1011.2M⊙) is observed to increase steadily with cosmic time. It is still unclear whether this trend originates from the size growth of individual galaxies (via, e.g. mergers and/or AGN feedback) or from the inclusion of larger galaxies entering the selection at later epochs (progenitor bias). We here build a data-driven, flexible theoretical framework to probe the structural evolution of MGs. We assign galaxies to dark matter haloes via stellar mass–halo mass (SMHM) relations with varying high-mass slopes and scatters σSMHM in stellar mass at fixed halo mass, and assign sizes to galaxies using an empirically motivated, constant and linear relationship between Re and the host dark matter halo radius Rh. We find that (1) the fast mean size growth of MGs is well reproduced independently of the shape of the input SMHM relation; (2) the numbers of compact MGs grow steadily until z ≳ 2 and fall off at lower redshifts, suggesting a lesser role of progenitor bias at later epochs; (3) a time-independent scatter σSMHM is consistent with a scenario in which compact star-forming MGs transition into quiescent MGs in a few 108 yr with a negligible structural evolution during the compact phase, while a scatter increasing at high redshift implies significant size growth during the star-forming phase. A robust measurement of the size function of MGs at high redshift can set strong constraints on the scatter of the SMHM relation and, by extension, on models of galaxy evolution.

3 Citations

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96 results found

Open accessJournal Article
Andy Lawrence1, Stephen J. Warren2, Omar Almaini3, Alastair C. Edge4  +19 moreInstitutions (11)
Abstract: Final published version including significant revisions. Twenty four pages, fourteen figures. Original version April 2006; final version published in MNRAS August 2007

Topics: Milky Way (53%), Quasar (51%)

2,388 Citations

Open accessJournal Article
David N. Reshef1, David N. Reshef2, David N. Reshef3, Yakir A. Reshef3  +13 moreInstitutions (6)
16 Dec 2011-Science
Abstract: Identifying interesting relationships between pairs of variables in large data sets is increasingly important. Here, we present a measure of dependence for two-variable relationships: the maximal information coefficient (MIC). MIC captures a wide range of associations both functional and not, and for functional relationships provides a score that roughly equals the coefficient of determination (R2) of the data relative to the regression function. MIC belongs to a larger class of maximal information-based nonparametric exploration (MINE) statistics for identifying and classifying relationships. We apply MIC and MINE to data sets in global health, gene expression, major-league baseball, and the human gut microbiota and identify known and novel relationships.

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1,852 Citations

Open accessJournal Article
Abstract: We present a simple, largely empirical but physically motivated model to interpret the mid- and far-infrared spectral energy distributions of galaxies consistently with the emission at ultraviolet, optical and near-infrared wavelengths. Our model relies on an existing angle-averaged prescription to compute the absorption of starlight by dust in stellar birth clouds and in the ambient interstellar medium (ISM) in galaxies. We compute the spectral energy distribution of the power reradiated by dust in stellar birth clouds as the sum of three components: a component of polycyclic aromatic hydrocarbons (PAHs); a mid-infrared continuum characterising the emission from hot grains at temperatures in the range 130–250 K; and a component of grains in thermal equilibrium with adjustable temperature in the range 30–60 K. In the ambient ISM, we fix for simplicity the relative proportions of these three components to reproduce the spectral shape of diffuse cirrus emission in the Milky Way, and we include a component of cold grains in thermal equilibrium with adjustable temperature in the range 15–25 K. Our model is both simple and versatile enough that it can be used to derive statistical constraints on the star formation histories and dust contents of large samples of galaxies using a wide range of ultraviolet, optical and infrared observations. We illustrate this by deriving median-likelihood estimates of the star formation rates, stellar masses, effective dust optical depths, dust masses, and relative strengths of different dust components of 66 well-studied nearby star-forming galaxies from the Spitzer Infrared Nearby Galaxy Survey (SINGS). We explore how the constraints derived in this way depend on the available spectral information. From our analysis of the SINGS sample, we conclude that the mid- and far-infrared colours of galaxies correlate strongly with the specific star formation rate, as well as with other galaxywide quantities connected to this parameter, such as the ratio of infrared luminosity between stellar birth clouds and the ambient ISM, the contributions by PAHs and grains in thermal equilibrium to the total infrared emission, and the ratio of dust mass to stellar mass. Our model can be straightforwardly applied to interpret ultraviolet, optical and infrared spectral energy distributions from any galaxy sample.

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Open accessJournal Article
Abstract: Spectroscopic+photometric redshifts, stellar mass estimates, and rest-frame colors from the 3D-HST survey are combined with structural parameter measurements from CANDELS imaging to determine the galaxy size-mass distribution over the redshift range 0 3 × 10{sup 9} M {sub ☉}, and steep, R{sub eff}∝M{sub ∗}{sup 0.75}, for early-type galaxies with stellar mass >2 × 10{sup 10} M {sub ☉}. The intrinsic scattermore » is ≲0.2 dex for all galaxy types and redshifts. For late-type galaxies, the logarithmic size distribution is not symmetric but is skewed toward small sizes: at all redshifts and masses, a tail of small late-type galaxies exists that overlaps in size with the early-type galaxy population. The number density of massive (∼10{sup 11} M {sub ☉}), compact (R {sub eff} < 2 kpc) early-type galaxies increases from z = 3 to z = 1.5-2 and then strongly decreases at later cosmic times.« less

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Open accessJournal Article
Mattia Negrello1, Rosalind Hopwood1, G. de Zotti, Asantha Cooray2  +93 moreInstitutions (46)
05 Nov 2010-
Abstract: Gravitational lensing is a powerful astrophysical and cosmological probe and is particularly valuable at submillimeter wavelengths for the study of the statistical and individual properties of dusty star-forming galaxies. However, the identification of gravitational lenses is often time-intensive, involving the sifting of large volumes of imaging or spectroscopic data to find few candidates. We used early data from the Herschel Astrophysical Terahertz Large Area Survey to demonstrate that wide-area submillimeter surveys can simply and easily detect strong gravitational lensing events, with close to 100% efficiency.