A population of z > 2 far-infrared Herschel-SPIRE-selected starbursts

C. M. Casey, S. Berta, M. Béthermin, J. Bock, C. Bridge, D. Burgarella, E. Chapin, S. C. Chapman, D. L. Clements, A. Conley, C. J. Conselice, A. Cooray, D. Farrah, E. Hatziminaoglou, R. J. Ivison, E. Le Floc'H, D. Lutz, G. Magdis, B. Magnelli, S. J. OliverM. J. Page, F. Pozzi, D. Rigopoulou, L. Riguccini, I. G. Roseboom, D. B. Sanders, Douglas Scott, N. Seymour, I. Valtchanov, J. D. Vieira, M. Viero, J. Wardlow

Research output: Contribution to journalArticlepeer-review

Abstract

We present spectroscopic observations for a sample of 36 Herschel-SPIRE 250-500 μm selected galaxies (HSGs) at 2 < z < 5 from the Herschel Multi-tiered Extragalactic Survey. Redshifts are confirmed as part of a large redshift survey of Herschel-SPIRE-selected sources covering ∼0.93 deg 2 in six extragalactic legacy fields. Observations were taken with the Keck I Low Resolution Imaging Spectrometer and the Keck II DEep Imaging Multi-Object Spectrograph. Precise astrometry, needed for spectroscopic follow-up, is determined by identification of counterparts at 24 μm or 1.4 GHz using a cross-identification likelihood matching method. Individual source luminosities range from log (LIR/L) = 12.5-13.6 (corresponding to star formation rates (SFRs) 500-9000 Myr-1, assuming a Salpeter initial mass function), constituting some of the most intrinsically luminous, distant infrared galaxies discovered thus far. We present both individual and composite rest-frame ultraviolet spectra and infrared spectral energy distributions. The selection of these HSGs is reproducible and well characterized across large areas of the sky in contrast to most z > 2 HyLIRGs in the literature, which are detected serendipitously or via tailored surveys searching only for high-z HyLIRGs; therefore, we can place lower limits on the contribution of HSGs to the cosmic star formation rate density (SFRD) at (7 ± 2) × 10-3 Myr-1 h 3 Mpc-3 at z ∼ 2.5, which is >10% of the estimated total SFRD of the universe from optical surveys. The contribution at z ∼ 4 has a lower limit of 3 × 10-3 Myr-1 h 3 Mpc-3, ≳20% of the estimated total SFRD. This highlights the importance of extremely infrared-luminous galaxies with high SFRs to the buildup of stellar mass, even at the earliest epochs.

Original languageEnglish (US)
Article number139
JournalAstrophysical Journal
Volume761
Issue number2
DOIs
StatePublished - Dec 10 2012

Keywords

  • galaxies: evolution
  • galaxies: high-redshift
  • galaxies: starburst
  • infrared: galaxies
  • submillimeter: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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