GRB 051008: a long, spectrally hard dust-obscured GRB in a Lyman-break galaxy at z ≈ 2.8

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Volnova, A. A., Pozanenko, A. S., Gorosabel, J., Perley, D. A., Frederiks, D. D., Kann, D. A., Rumyantsev, V. V., Biryukov, V. V., Burkhonov, O., Castro-Tirado, A. J., Ferrero, P., Golenetskii, S. V., Klose, S., Loznikov, V. M., Minaev, P. Yu., Stecklum, B., Svinkin, D. S., Tsvetkova, A. E., de Ugarte Postigo, A., Ulanov, M. V.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Royal Astronomical Society 2014
• Subjects: gamma-ray burst: individual: dark galaxies: distances and redshifts galaxies: high-redshift galaxies: photometry; Gemini; Norway; Observatorio; Iceland
• Online Access: https://doi.org/10.1093/mnras/stu999

We present observations of the dark gamma-ray burst GRB 051008 provided by Swift/BAT, Swift/XRT, Konus-WIND, INTEGRAL/SPI-ACS in the high-energy domain and the Shajn, Swift/UVOT, Tautenburg, NOT, Gemini and Keck I telescopes in the optical and near-infrared bands. The burst was detected only in gamma- and X-rays and neither a prompt optical nor a radio afterglow was detected down to deep limits. We identified the host galaxy of the burst, which is a typical Lyman-break galaxy (LBG) with R-magnitude of 24.06 ± 0.10 mag. A redshift of the galaxy of z=2.77^(+0.15)_(−0.20) is measured photometrically due to the presence of a clear, strong Lyman-break feature. The host galaxy is a small starburst galaxy with moderate intrinsic extinction (A_V = 0.3) and has a star formation rate of ∼60 M_⊙ yr^(−1) typical for LBGs. It is one of the few cases where a GRB host has been found to be a classical LBG. Using the redshift we estimate the isotropic-equivalent radiated energy of the burst to be E_(iso) = (1.15 ± 0.20) × 10^(54) erg. We also provide evidence in favour of the hypothesis that the darkness of GRB 051008 is due to local absorption resulting from a dense circumburst medium. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 May 16. Received 2014 May 8; in original form 2014 March 5. First published online June 27, 2014. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. We are grateful to S.N. Dodonov, T.A. Fatkhullin, M.V. Barkov, O.V. Egorov, M. Salvato, D.I. Karasyov, and V.A. Kolesnikov for useful discussions. AAV, ASP and PYuM were supported by the program 'Origin, structure, and evolution of objects in the Universe' funded by the Russian Academy of Sciences and RFBR grants 12-02-01336-a, 13-01-92204-Mong, 14-02-10015-K. JG and ...