A revised host galaxy association for GRB 020819B: a high-redshift dusty starburst, not a low-redshift gas-poor spiral

Daniel A. Perley, Thomas Krühler, Patricia Schady, Michal J. Michalowski, Christina C. Thöne, Dirk Petry, John F. Graham, Jochen Greiner, Sylvio Klose, Steve Schulze, Sam Kim

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Abstract

The purported spiral host galaxy of GRB 020819B at z = 0.41 has been seminal in establishing our view of the diversity of long-duration gamma-ray burst environments: Optical spectroscopy of this host provided evidence that gamma-ray bursts (GRBs) can form even at high metallicities, whereas millimetric observations suggested that GRBs may preferentially form in regions with minimal molecular gas. We report new observations from the Very Large Telescope (Multi Unit Spectroscopic Explorer and X-shooter), which demonstrate that the purported host is an unrelated foreground galaxy. The probable radio afterglow is coincident with a compact, highly star forming, dusty galaxy at z = 1.9621. The revised redshift naturally explains the apparent non-detection of CO(3–2) line emission at the afterglow site from the Atacama Large Millimetre Observatory. There is no evidence that molecular gas properties in GRB host galaxies are unusual, and limited evidence that GRBs can form readily at a super-Solar metallicity.
Original languageEnglish
Pages (from-to)L89-L93
JournalMonthly Notices of the Royal Astronomical Society
Volume465
Issue number1
Early online date26 Oct 2016
DOIs
Publication statusPublished - 1 Feb 2017

Keywords

  • gamma-ray burst: individual: GRB 020819B, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies

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