title: The formation of submillimetre-bright galaxies from gas infall over a billion years.
abstract: Submillimetre-bright galaxies at high redshift are the most luminous, heavily star-forming galaxies in the Universe and are characterized by prodigious emission in the far-infrared, with a flux of at least five millijanskys at a wavelength of 850 micrometres. They reside in haloes with masses about 10(13) times that of the Sun, have low gas fractions compared to main-sequence disks at a comparable redshift, trace complex environments and are not easily observable at optical wavelengths. Their physical origin remains unclear. Simulations have been able to form galaxies with the requisite luminosities, but have otherwise been unable to simultaneously match the stellar masses, star formation rates, gas fractions and environments. Here we report a cosmological hydrodynamic galaxy formation simulation that is able to form a submillimetre galaxy that simultaneously satisfies the broad range of observed physical constraints. We find that groups of galaxies residing in massive dark matter haloes have increasing rates of star formation that peak at collective rates of about 500-1,000 solar masses per year at redshifts of two to three, by which time the interstellar medium is sufficiently enriched with metals that the region may be observed as a submillimetre-selected system. The intense star formation rates are fuelled in part by the infall of a reservoir gas supply enabled by stellar feedback at earlier times, not through major mergers. With a lifetime of nearly a billion years, our simulations show that the submillimetre-bright phase of high-redshift galaxies is prolonged and associated with significant mass buildup in early-Universe proto-clusters, and that many submillimetre-bright galaxies are composed of numerous unresolved components (for which there is some observational evidence).
authors.affiliation: Haverford College, 370 West Lancaster Avenue, Haverford, Pennsylvania 19041, USA.
authors.forename: Desika
authors.initials: D
authors.lastname: Narayanan
authors.affiliation: National Center for Supercomputing Applications, University of Illinois, 1205 West Clark Street, Urbana-Champaign, Illinois 61820, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Turk
authors.affiliation: Department of Astronomy and Theoretical Astrophysics Center, University of California, Berkeley, California 94720, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Feldmann
authors.affiliation: Max Planck Institute for Astronomy, Konigstuhl 17, D-69117 Heidelberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Robitaille
authors.affiliation: TAPIR, California Institute of Technology, MC 350-17, Pasadena, California 91125, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Hopkins
authors.affiliation: University of the Western Cape, Bellville, Cape Town 7535, South Africa.|Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, Arizona 85721, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Thompson
authors.affiliation: TAPIR, California Institute of Technology, MC 350-17, Pasadena, California 91125, USA.|Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Hayward
authors.affiliation: Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, Arizona 85721, USA.|Whitman College, 345 Boyer Avenue, Walla Walla, Washington 99362, USA.
authors.forename: David
authors.initials: D
authors.lastname: Ball
authors.affiliation: CIERA, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
authors.forename: Claude-André
authors.initials: CA
authors.lastname: Faucher-Giguère
authors.affiliation: CASS, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.
authors.forename: Dušan
authors.initials: D
authors.lastname: Kereš