Dusty star-forming galaxies at high redshift

Abstract

Far-infrared and submillimeter wavelength surveys have now established the important role of dusty, star-forming galaxies (DSFGs) in the assembly of stellar mass and the evolution of massive galaxies in the Universe. The brightest of these galaxies have infrared luminosities in excess of 10 13 L with implied star-formation rates of thousands of solar masses per year. They represent the most intense starbursts in the Universe, yet many are completely optically obscured. Their easy detection at submm wavelengths is due to dust heated by ultraviolet radiation of newly forming stars. When summed up, all of the dusty, star-forming galaxies in the Universe produce an infrared radiation field that has an equal energy density as the direct starlight emission from all galaxies visible at ultraviolet and optical wavelengths. The bulk of this infrared extragalactic background light emanates from galaxies as diverse as gas-rich disks to mergers of intense starbursting galaxies. Major advances in far-infrared instrumentation in recent years, both spacebased and ground-based, has led to the detection of nearly a million DSFGs, yet our understanding of the underlying astrophysics that govern the start and end of the dusty starburst phase is still in nascent stage. This review is aimed at summarizing the current status of DSFG studies, focusing especially on the detailed characterization of the bestunderstood subset (submillimeter galaxies, who were summarized in the last review of this field over a decade ago, Blain et al. 2002), but also the selection and characterization of more recently discovered DSFG populations. We review DSFG population statistics, their physical properties including dust, gas and stellar contents, their environments, and current theoretical models related to the formation and evolution of these galaxies.

A Total Molecular Gas Mass Census in Z ∼ 2–3 Star-Forming Galaxies: Low-J Co Excitation Probes of Galaxies’ Evolutionary States

“…While high-z quasars are generally rare, a significant fraction have far-infrared (FIR) luminosities >10 13 L e (e.g., Wang et al 2008;Leipski et al 2013Leipski et al , 2014, which are mostly due to high star-formation rates (SFRs) (>1000 M e yr −1 ) fed by molecular gas reservoirs on the order of 10 10 -10 11  M (e.g., Carilli & Walter 2013, and references therein). Among FIR-bright galaxies near the peak of cosmic growth, submillimeter galaxies (SMGs; Casey et al 2014 and references therein) are substantially more common than FIRluminous quasarsbut have comparable L FIR , star-formation rates, molecular gas masses, and dynamical masses (e.g., Genzel et al 2003;Tecza et al 2004;Tacconi et al 2006Tacconi et al , 2008Riechers et al 2008aRiechers et al , 2008bIvison et al 2010a;Hainline et al 2011;Hodge et al 2012). Both SMGs and optically selected AGNs (quasars) are suspected to trace massive structure formation at high redshift since both populations have similar clustering properties (e.g., Blain et al 2004;Hickox et al 2012).…”

The discovery of gas-rich, dusty starbursts in luminous reddened quasars atz∼ 2.5 with ALMA

“…Over the last two decades, surveys starting with the SCUBA bolometer on the James Clerk Maxwell Telescope (JCMT) and, more recently, using the Herschel space satellite, have led to the discovery of large populations of far infrared (FIR) and submillimetre bright starburst galaxies (SMGs) at the main epoch of galaxy formation (e.g. Smail et al 1997;Blain et al 1999;Casey et al 2014). Molecular gas detections are now being assembled for many tens to hundreds of such galaxies (e.g.…”

The bias of the submillimetre galaxy population: SMGs are poor tracers of the most-massive structures in thez ∼ 2 Universe

“…Submillimetre-selected galaxies (SMGs; see Casey et al 2014 for a recent review), with typical infrared (IR) luminosities of LIR 5×10 12 L , represent the rarest and most extreme examples of star forming galaxies. The LIR of an SMG implies an immense star formation rate, typically SFR ∼ 500 − 1000 M yr −1 , assuming that there is not a significant contribution to LIR from deeply obscured AGN.…”