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The Host Galaxy of GRB 990123

Bloom, J. S. and Odewahn, S. C. and Djorgovski, S. G. and Kulkarni, S. R. and Harrison, F. A. and Koresko, C. and Neugebauer, G. and Armus, L. and Frail, D. A. and Gal, R. R. and Sari, R. and Squires, G. and Illingworth, G. and Kelson, D. and Chaffee, F. H. and Goodrich, R. and Feroci, M. and Costa, E. and Piro, L. and Frontera, F. and Mao, S. and Akerlof, C. and McKay, T. A. (1999) The Host Galaxy of GRB 990123. Astrophysical Journal, 518 (1). L1-L4. ISSN 0004-637X. doi:10.1086/312059.

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We present deep images of the field of GRB 990123 obtained in a broadband UV/visible bandpass with the Hubble Space Telescope (HST) and deep near-infrared images obtained with the Keck I 10 m telescope. The HST image reveals that the optical transient (OT) is offset by 0farcs67 (5.8 kpc in projection) from an extended, apparently interacting galaxy. This galaxy, which we conclude is the host galaxy of GRB 990123, is the most likely source of the absorption lines of metals at a redshift of z=1.6 seen in the spectrum of the OT. With magnitudes of Gunn-r = 24.5 ± 0.2 and K = 22.1±0.3 mag, this corresponds to an L ~ 0.5L$\mathstrut{_{*}}$ galaxy, assuming that it is located at z = 1.6. The estimated unobscured star formation rate is ≈4 M_☉ yr^(−1), which is typical for normal galaxies at comparable redshifts. There is no evidence for strong gravitational lensing magnification of this burst, and some alternative explanation for its remarkable energetics (such as beaming) may therefore be required. The observed offset of the OT from the nominal host center, the absence of broad absorption lines in the afterglow spectrum, and the relatively blue continuum of the host do not support the notion that gamma-ray bursts (GRBs) originate from active galactic nuclei or massive black holes. Rather, the data are consistent with models of GRBs that involve the death and/or merger of massive stars. Indeed, the HST image suggests an intimate connection between GRB 990123 and a star-forming region.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bloom, J. S.0000-0002-7777-216X
Djorgovski, S. G.0000-0002-0603-3087
Kulkarni, S. R.0000-0001-5390-8563
Harrison, F. A.0000-0003-2992-8024
Armus, L.0000-0003-3498-2973
Sari, R.0000-0002-1084-3656
Squires, G.0000-0002-1977-5717
Illingworth, G.0000-0002-8096-2837
Mao, S.0000-0001-8317-2788
Additional Information:© 1999 American Astronomical Society. Received 12 February 1999. Accepted 1 April 1999. Published 29 April 1999. We are grateful to S. Beckwith of STScI for the allocation of the director's discretionary time for this project and to the entire BeppoSAX team and the staff of W. M. Keck Observatory for their efforts. We also thank L. Ferrarese for aiding us with HST observing and the anonymous referee for helpful and clarifying comments. This work was supported in part by a grant from STScI, grants from the NSF and NASA, and the Bressler Foundation.
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Space Telescope Science InstituteUNSPECIFIED
Bressler FoundationUNSPECIFIED
Subject Keywords:cosmology: miscellaneous; cosmology: observations; gamma rays: bursts
Issue or Number:1
Record Number:CaltechAUTHORS:20170223-070422097
Persistent URL:
Official Citation:J. S. Bloom et al 1999 ApJ 518 L1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:74483
Deposited By: Ruth Sustaita
Deposited On:23 Feb 2017 17:15
Last Modified:11 Nov 2021 05:27

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