The largest Herschel extragalactic surveys, H-ATLAS and HerMES, have selected a sample of "ultrared" dusty star-forming galaxies (DSFGs) with rising SPIRE flux densities (S500 > S350 > S250; the ...so-called "500 m risers") as an efficient way for identifying DSFGs at higher redshift (z > 4). In this paper, we present a large Spitzer follow-up program of 300 Herschel ultrared DSFGs. We have obtained high-resolution Atacama Large Millimeter/submillimeter Array, Northern Extended Millimeter Array, and SMA data for 63 of them, which allow us to securely identify the Spitzer/IRAC counterparts and classify them as gravitationally lensed or unlensed. Within the 63 ultrared sources with high-resolution data, ∼65% appear to be unlensed and ∼27% are resolved into multiple components. We focus on analyzing the unlensed sample by directly performing multiwavelength spectral energy distribution modeling to derive their physical properties and compare with the more numerous z ∼ 2 DSFG population. The ultrared sample has a median redshift of 3.3, stellar mass of 3.7 × 1011 M , star formation rate (SFR) of 730 M yr−1, total dust luminosity of 9.0 × 1012 L , dust mass of 2.8 × 109 M , and V-band extinction of 4.0, which are all higher than those of the ALESS DSFGs. Based on the space density, SFR density, and stellar mass density estimates, we conclude that our ultrared sample cannot account for the majority of the star-forming progenitors of the massive, quiescent galaxies found in infrared surveys. Our sample contains the rarer, intrinsically most dusty, luminous, and massive galaxies in the early universe that will help us understand the physical drivers of extreme star formation.
DSFGs dominate the cosmic star formation rate (SFR) at z > 0.7, are 2 - 3 orders of magnitude more populous at z = 2 than locally, and have SFRs of tens to thousands of solar masses per year. Despite ...their prodigious SFR, they are heavily dust obscured, with estimates suggesting that optical/UV surveys alone miss half the star formation in the Universe. Furthermore, DSFGs are believed to be the evolutionary progenitors to the massive elliptical galaxies that today inhabit the cores of massive galaxy clusters. DSFGs however remain poorly constrained, with few constraints on their contribution to the cosmic SFR density above z > 4, disagreement over whether single-dish observations accurately reflect the underlying population, and uncertainty about DSFGs in clusters, particularly whether they trace massive overdensities at their epoch. This thesis presents a series of results that set out to address some of these questions. To begin with, and by cross-matching Planck and Herschel data, we identify 27 candidate protoclusters by searching for overdensities of DSFGs. Their colours indicate they likely lie at z = 2 − 3, their flux density is 3x brighter than predicted from models, and fitting modified blackbodies to their photometry suggests they have total SFRs of several thousand solar masses per year. We additionally present the results of an interferometric program targeting 36 single-dish DSFGs at z ∼ 4. We assess their multiplicity, finding that whilst ∼ 45% are blends of multiple sources, there are a number of highly luminous, possibly lensed, singular sources. Finally, we present the serendipitous detection of a SPIRE dropout, a source detected at 850 μm but not at any shorter wavelength, likely at z > 6, and we discuss the application of its selection to wider surveys. In closing, we discuss the future of FIR/sub-mm astronomy, new directions of the work begun here, and the challenges that remain for the field.
ABSTRACT We present a source-plane reconstruction of a Herschel and Planck-detected gravitationally lensed dusty star-forming galaxy (DSFG) at z = 1.68 using Hubble, Submillimeter Array (SMA), and ...Keck observations. The background submillimeter galaxy (SMG) is strongly lensed by a foreground galaxy cluster at z = 0.997 and appears as an arc with a length of ∼15″ in the optical images. The continuum dust emission, as seen by SMA, is limited to a single knot within this arc. We present a lens model with source-plane reconstructions at several wavelengths to show the difference in magnification between the stars and dust, and highlight the importance of multi-wavelength lens models for studies involving lensed DSFGs. We estimate the physical properties of the galaxy by fitting the flux densities to model spectral energy distributions leading to a magnification-corrected star-formation rate (SFR) of 390 60 M yr−1 and a stellar mass of . These values are consistent with high-redshift massive galaxies that have formed most of their stars already. The estimated gas-to-baryon fraction, molecular gas surface density, and SFR surface density have values of 0.43 0.13, 350 200 pc−2, and M yr−1 kpc−2, respectively. The ratio of SFR surface density to molecular gas surface density puts this among the most star-forming systems, similar to other measured SMGs and local ULIRGs.
The largest Herschel extragalactic surveys, H-ATLAS and HerMES, have selected a sample of "ultrared" dusty, star-forming galaxies (DSFGs) with rising SPIRE flux densities (\(S_{500} > S_{350} > ...S_{250}\); so-called "500 \(\mu\)m-risers") as an efficient way for identifying DSFGs at higher redshift (\(z > 4\)). In this paper, we present a large Spitzer follow-up program of 300 Herschel ultrared DSFGs. We have obtained high-resolution ALMA, NOEMA, and SMA data for 63 of them, which allow us to securely identify the Spitzer/IRAC counterparts and classify them as gravitationally lensed or unlensed. Within the 63 ultrared sources with high-resolution data, \(\sim\)65% appear to be unlensed, and \(\sim\)27% are resolved into multiple components. We focus on analyzing the unlensed sample by directly performing multi-wavelength spectral energy distribution (SED) modeling to derive their physical properties and compare with the more numerous \(z \sim 2\) DSFG population. The ultrared sample has a median redshift of 3.3, stellar mass of 3.7 \(\times\) 10\(^{11}\) \(M_{\odot}\), star formation rate (SFR) of 730 \(M_{\odot}\)yr\(^{-1}\), total dust luminosity of 9.0 \(\times\) 10\(^{12}\) \(L_{\odot}\), dust mass of 2.8 \(\times\) 10\(^9\) \(M_{\odot}\), and V-band extinction of 4.0, which are all higher than those of the ALESS DSFGs. Based on the space density, SFR density, and stellar mass density estimates, we conclude that our ultrared sample cannot account for the majority of the star-forming progenitors of the massive, quiescent galaxies found in infrared surveys. Our sample contains the rarer, intrinsically most dusty, luminous and massive galaxies in the early universe that will help us understand the physical drivers of extreme star formation.
We present the SCUBA-2 850 \({\mu}m\) component of JINGLE, the new JCMT large survey for dust and gas in nearby galaxies, which with 193 galaxies is the largest targeted survey of nearby galaxies at ...850 \({\mu}m\). We provide details of our SCUBA-2 data reduction pipeline, optimised for slightly extended sources, and including a calibration model adjusted to match conventions used in other far-infrared data. We measure total integrated fluxes for the entire JINGLE sample in 10 infrared/submillimetre bands, including all WISE, Herschel-PACS, Herschel-SPIRE and SCUBA-2 850 \({\mu}m\) maps, statistically accounting for the contamination by CO(J=3-2) in the 850 \({\mu}m\) band. Of our initial sample of 193 galaxies, 191 are detected at 250 \({\mu}m\) with a \(\geq\) 5\({\sigma}\) significance. In the SCUBA-2 850 \({\mu}m\) band we detect 126 galaxies with \(\geq\) 3\({\sigma}\) significance. The distribution of the JINGLE galaxies in far-infrared/sub-millimetre colour-colour plots reveals that the sample is not well fit by single modified-blackbody models that assume a single dust-emissivity index \((\beta)\). Instead, our new 850 \({\mu}m\) data suggest either that a large fraction of our objects require \(\beta < 1.5\), or that a model allowing for an excess of sub-mm emission (e.g., a broken dust emissivity law, or a very cold dust component 10 K) is required. We provide relations to convert far-infrared colours to dust temperature and \(\beta\) for JINGLE-like galaxies. For JINGLE the FIR colours correlate more strongly with star-formation rate surface-density rather than the stellar surface-density, suggesting heating of dust is greater due to younger rather than older stellar-populations, consistent with the low proportion of early-type galaxies in the sample.
JINGLE is a new JCMT legacy survey designed to systematically study the cold interstellar medium of galaxies in the local Universe. As part of the survey we perform 850um continuum measurements with ...SCUBA-2 for a representative sample of 193 Herschel-selected galaxies with M*>10^9Msun, as well as integrated CO(2-1) line fluxes with RxA3m for a subset of 90 of these galaxies. The sample is selected from fields covered by the Herschel-ATLAS survey that are also targeted by the MaNGA optical integral-field spectroscopic survey. The new JCMT observations combined with the multi-wavelength ancillary data will allow for the robust characterization of the properties of dust in the nearby Universe, and the benchmarking of scaling relations between dust, gas, and global galaxy properties. In this paper we give an overview of the survey objectives and details about the sample selection and JCMT observations, present a consistent 30 band UV-to-FIR photometric catalog with derived properties, and introduce the JINGLE Main Data Release (MDR). Science highlights include the non-linearity of the relation between 850um luminosity and CO line luminosity, and the serendipitous discovery of candidate z>6 galaxies.
Lensing of the CMB is now a well-developed probe of large-scale clustering over a broad range of redshifts. By exploiting the non-Gaussian imprints of lensing in the polarization of the CMB, the CORE ...mission can produce a clean map of the lensing deflections over nearly the full-sky. The number of high-S/N modes in this map will exceed current CMB lensing maps by a factor of 40, and the measurement will be sample-variance limited on all scales where linear theory is valid. Here, we summarise this mission product and discuss the science that it will enable. For example, the summed mass of neutrinos will be determined to an accuracy of 17 meV combining CORE lensing and CMB two-point information with contemporaneous BAO measurements, three times smaller than the minimum total mass allowed by neutrino oscillations. In the search for B-mode polarization from primordial gravitational waves with CORE, lens-induced B-modes will dominate over instrument noise, limiting constraints on the gravitational wave power spectrum amplitude. With lensing reconstructed by CORE, one can "delens" the observed polarization internally, reducing the lensing B-mode power by 60%. This improves to 70% by combining lensing and CIB measurements from CORE, reducing the error on the gravitational wave amplitude by 2.5 compared to no delensing (in the null hypothesis). Lensing measurements from CORE will allow calibration of the halo masses of the 40000 galaxy clusters that it will find, with constraints dominated by the clean polarization-based estimators. CORE can accurately remove Galactic emission from CMB maps with its 19 frequency channels. We present initial findings that show that residual Galactic foreground contamination will not be a significant source of bias for lensing power spectrum measurements with CORE. abridged
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