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 deg2 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 (L IR/L ⊙) = 12.5-13.6 (corresponding to star formation rates (SFRs) 500-9000 M ⊙ yr-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 M ⊙ yr-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 M ⊙ yr-1 h 3 Mpc-3, gsim20% 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.
C. M. Casey, S. Berta, M. Béthermin, J. Bock, C. Bridge, D. Burgarella, et al. (2012). A POPULATION OFz> 2 FAR-INFRAREDHERSCHEL-SPIRE-SELECTED STARBURSTS. THE ASTROPHYSICAL JOURNAL, 761, 139-162 [10.1088/0004-637X/761/2/139].
A POPULATION OFz> 2 FAR-INFRAREDHERSCHEL-SPIRE-SELECTED STARBURSTS
POZZI, FRANCESCA;
2012
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 deg2 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 (L IR/L ⊙) = 12.5-13.6 (corresponding to star formation rates (SFRs) 500-9000 M ⊙ yr-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 M ⊙ yr-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 M ⊙ yr-1 h 3 Mpc-3, gsim20% 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
