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The Star Formation Rate and Metallicity of the Host Galaxy of the Dark GRB 080325 at z = 1.78

Hashimoto, T and Perley, DA and Ohta, K and Aoki, K and Tanaka, I and Niino, Y and Yabe, K and Kawai, N (2015) The Star Formation Rate and Metallicity of the Host Galaxy of the Dark GRB 080325 at z = 1.78. The Astrophysical Journal, 806 (2). ISSN 1538-4357

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Abstract

We present near-infrared spectroscopy of the host galaxy of the dark gamma-ray burst (GRB) 080325 using Subaru/Multi-Object Infrared Camera and Spectrograph. The obtained spectrum provides a clear detection of H emission and marginal [Nii]λ6584. The host is a massive (M∗ ∼ 1011 Mȯ), dusty (Av ∼ 1.2) star-forming galaxy at z = 1.78. The extinction-corrected star formation rate (SFR) calculated from the H luminosity (35.6-47.0 Mȯ yr-1) is typical among GRB host galaxies (and star-forming galaxies generally) at z > 1; however, the specific SFR is lower than for normal star-forming galaxies at redshift ∼1.6, in contrast to the high specific SFR measured for many of other GRB hosts. The metallicity of the host is estimated to be 12 + log(O/H)KK04 = 8.88. We emphasize that this is one of the most massive host galaxies at z > for which metallicity is measured with emission-line diagnostics. The metallicity is fairly high among GRB hosts, however, this is still lower than the metallicity of normal star-forming galaxies of the same mass at z ∼ 1.6. The metallicity offset from normal star-forming galaxies is close to a typical value of other GRB hosts and indicates that GRB host galaxies are uniformly biased toward low metallicity over a wide range of redshifts and stellar masses. The low-metallicity nature of the GRB 080325 host likely cannot be attributed to the fundamental metallicity relation of star-forming galaxies because it is a metal-poor outlier from the relation and has a low specific star formation rate. Thus, we conclude that metallicity is important to the mechanism that produced this GRB. © 2015. The American Astronomical Society. All rights reserved.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical And Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (Incl. Structural)
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: American Astronomical Society
Date Deposited: 22 Feb 2017 08:59
Last Modified: 07 Sep 2017 14:44
DOI or Identification number: 10.1088/0004-637X/806/2/250
URI: http://researchonline.ljmu.ac.uk/id/eprint/5690

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