A Population of Massive, Luminous Galaxies Hosting Heavily Dust-obscured Gamma-Ray Bursts: Implications for the Use of GRBs as Tracers of Cosmic Star Formation

Creators: Perley, D. A.; Levan, A. J.; Tanvir, N. R.; Cenko, S. B.; Bloom, J. S.; Hjorth, J.; Krühler, T.; Filippenko, A. V.; Fruchter, A.; Fynbo, J. P. U.; Jakobsson, P.; Kalirai, J.; Milvang-Jensen, B.; Morgan, A. N.; Prochaska, J. X.; Silverman, J. M.

Abstract

We present observations and analysis of the host galaxies of 23 heavily dust-obscured gamma-ray bursts (GRBs) observed by the Swift satellite during the years 2005-2009, representing all GRBs with an unambiguous host-frame extinction of AV > 1 mag from this period. Deep observations with Keck, Gemini, Very Large Telescope, Hubble Space Telescope, and Spitzer successfully detect the host galaxies and establish spectroscopic or photometric redshifts for all 23 events, enabling us to provide measurements of the intrinsic host star formation rates, stellar masses, and mean extinctions. Compared to the hosts of unobscured GRBs at similar redshifts, we find that the hosts of dust-obscured GRBs are (on average) more massive by about an order of magnitude and also more rapidly star forming and dust obscured. While this demonstrates that GRBs populate all types of star-forming galaxies, including the most massive, luminous systems at z ≈ 2, at redshifts below 1.5 the overall GRB population continues to show a highly significant aversion to massive galaxies and a preference for low-mass systems relative to what would be expected given a purely star-formation-rate-selected galaxy sample. This supports the notion that the GRB rate is strongly dependent on metallicity, and may suggest that the most massive galaxies in the universe underwent a transition in their chemical properties ~9 Gyr ago. We also conclude that, based on the absence of unobscured GRBs in massive galaxies and the absence of obscured GRBs in low-mass galaxies, the dust distributions of the lowest-mass and the highest-mass galaxies are relatively homogeneous, while intermediate-mass galaxies (~10^9 M_☉) have diverse internal properties.

Additional Information

© 2013 American Astronomical Society. Received 2013 January 24; accepted 2013 September 27; published 2013 November 12. We thank D. Malesani for early access to the VLT photometry and redshifts, and for additional assistance with the TOUGH data. We acknowledge useful conversations with R. Chary, and thank M. Michalowski, D.A. Kann, and the referee for helpful commentary on the manuscript. We are grateful to E. Petigura for assistance with the Keck-NIRC observations and S. Kulkarni for some additional LRIS observations. We also thank M. Kajisawa for assistance with providing and interpreting the Subaru MODS observations. Support for this work was provided by NASA through Hubble Fellowship grant HST-HF-51296.01-A awarded by the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., for NASA, under contract NAS 5-26555. The Dark Cosmology Centre is supported by the Danish National Science Foundation. J.P.U.F. and B.M.J. acknowledge support from ERC-StG grant EGGS-278202. T.K. acknowledges support by the European Commission under the Marie Curie Intra-European Fellowship Programme in FP7. A.V.F. and his group acknowledge generous financial assistance from Gary & Cynthia Bengier, the Richard & Rhoda Goldman Fund, the Christopher R. Redlich Fund, NASA/Swift grants NNX10AI21G and NNX12AD73G, the TABASGO Foundation, and NSF grant AST-1211916. J.X.P. acknowledges support from NASA/Swift grants NNX07AE94G and NNX12AD74G. This work is based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs GO-10908, 11343, 11840, 12307, 12378, 12764, and 12949. Support for HST programs GO-11840, GO-12378, and GO-12674 was provided by NASA through a grant from STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA; the Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We wish to extend special thanks to those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Partial support for this work was provided by NASA through an award issued by JPL/Caltech. It is also based in part on observations obtained at the Gemini Observatory, which is operated by AURA, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the NSF (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Ministerio de Ciencia, Tecnología e Innovaciόn Productiva (Argentina). Observations were acquired under Program IDs GN-2006A-Q-14, GN-2006B-Q-21, GN-2007A-Q-19, GS-2008A-Q-20, GN-2007B-Q-99, GN-2008B-Q-6, GN-2009A-Q-26, GN-2009AQ-84, GN-2010A-C-8, and GN-2010B-C-2. PAIRITEL is operated by the Smithsonian Astrophysical Observatory (SAO) and was made possible by a grant from the Harvard University Milton Fund, a camera loan from the University of Virginia, and continued support of the SAO and UC Berkeley. The PAIRITEL project is further supported by NASA/Swift Guest Investigator grant NNX08AN84G. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. This research also made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. It is a pleasure to thank all members of the Swift team, who built and continue to operate this highly successful mission. Facilities: Swift, Keck:I (LRIS, NIRC), HST (WFC3), Gemini:Gillett (GMOS, NIRI), Spitzer (IRAC)

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