A study of the prompt and afterglow emission of the Short GRB 061201

Context. Our knowledge of the intrinsic properties of short duration Gamma-Ray Bursts has relied, so far, only upon a few cases for which the estimate of the distance and an extended, multiwavelength monitoring of the afterglow have been obtained. Aims. We carried out multiwavelength observations of the short GRB 061201 aimed at estimating its distance and studying its properties. Methods. We performed a spectral and timing analysis of the prompt and afterglow emission and discuss the results in the context of the standard fireball model. Results. A clear temporal break was observed in the X-ray light curve about 40 min after the burst trigger. We find that the spectral and timing behaviour of the X-ray afterglow is consistent with a jet origin of the observed break, although the optical data can not definitively confirm this and other scenarios are possible. No underlying host galaxy down to R ∼ 26 mag was found after fading of the optical afterglow. Thus, no secure redshift could be measured for this burst. The nearest galaxy is at z = 0.111 and shows evidence of star formation activity. We discuss the association of GRB 061201 with this galaxy and with the ACO S 995 galaxy cluster, from which the source is at an angular distance of 17 �� and 8.5 � , respectively. We also test the association with a possible undetected, positionally consistent galaxy at z ∼ 1. In all these cases, in the jet interpretation, we find a jet opening angle of 1–2 degrees.

[1]  N. Gehrels,et al.  Making a Short Gamma-Ray Burst from a Long One: Implications for the Nature of GRB 060614 , 2006, astro-ph/0612238.

[2]  P. B. Cameron,et al.  A New Population of High-Redshift Short-Duration Gamma-Ray Bursts , 2006, astro-ph/0611128.

[3]  T. Sakamoto,et al.  A new γ-ray burst classification scheme from GRB 060614 , 2006, Nature.

[4]  P. Conconi,et al.  REM observations of GRB 060418 and GRB 060607A: the onset of the afterglow and the initial fireball Lorentz factor determination , 2006, astro-ph/0612607.

[5]  N. Gehrels,et al.  Testing the Standard Fireball Model of Gamma-Ray Bursts Using Late X-Ray Afterglows Measured by Swift , 2006, astro-ph/0612031.

[6]  N. Gehrels,et al.  Jet Breaks in Short Gamma-Ray Bursts. II. The Collimated Afterglow of GRB 051221A , 2006, astro-ph/0604320.

[7]  K. Pedersen,et al.  Are short γ-ray bursts collimated? GRB 050709, a flare but no break , 2006, astro-ph/0604153.

[8]  N. Gehrels,et al.  Evidence for chromatic X-ray light-curve breaks in Swift GRB afterglows and their theoretical implications , 2006, astro-ph/0604105.

[9]  D. Frail,et al.  The Afterglow, Energetics, and Host Galaxy of the Short-Hard Gamma-Ray Burst 051221a , 2006, astro-ph/0601455.

[10]  J. Norris,et al.  Short Gamma-Ray Bursts with Extended Emission , 2006, astro-ph/0601190.

[11]  D. Burrows,et al.  A refined position catalogue of the Swift XRT afterglows , 2005, astro-ph/0511604.

[12]  M. M. Kasliwal,et al.  The afterglow of GRB 050709 and the nature of the short-hard γ-ray bursts , 2005, Nature.

[13]  L. A. Antonelli,et al.  Optical emission from GRB 050709 : a short/hard GRB in a star-forming galaxy , 2005, astro-ph/0509144.

[14]  P. B. Cameron,et al.  The afterglow and elliptical host galaxy of the short γ-ray burst GRB 050724 , 2005, Nature.

[15]  T. Sakamoto,et al.  A short γ-ray burst apparently associated with an elliptical galaxy at redshift z = 0.225 , 2005, Nature.

[16]  T. Piran,et al.  The Luminosity and Angular Distributions of Long-Duration Gamma-Ray Bursts , 2003, astro-ph/0311488.

[17]  J. Hjorth,et al.  UV star-formation rates of GRB host galaxies , 2004, astro-ph/0407066.

[18]  G. Ghirlanda,et al.  The Collimation-corrected Gamma-Ray Burst Energies Correlate with the Peak Energy of Their νFν Spectrum , 2004, astro-ph/0405602.

[19]  Alan A. Wells,et al.  The Swift Gamma-Ray Burst Mission , 2004, astro-ph/0405233.

[20]  Scott D. Barthelmy,et al.  The Burst Alert Telescope (BAT) on the SWIFT Midex Mission , 2004, SPIE Optics + Photonics.

[21]  J. Cordes,et al.  PSR J1829+2456: a relativistic binary pulsar , 2004, astro-ph/0403553.

[22]  Peter W. A. Roming,et al.  The Swift Ultra-Violet/Optical Telescope , 2002, SPIE Optics + Photonics.

[23]  D. Watson,et al.  The Swift X-Ray Telescope , 1999, SPIE Optics + Photonics.

[24]  R. Bouwens,et al.  Faint Galaxies in Deep Advanced Camera for Surveys Observations , 2004 .

[25]  N. Masetti,et al.  Intrinsic spectra and energetics of BeppoSAX Gamma-Ray Bursts with known redshifts , 2002, astro-ph/0205230.

[26]  S. Djorgovski,et al.  Beaming in Gamma-Ray Bursts: Evidence for a Standard Energy Reservoir , 2001, astro-ph/0102282.

[27]  Re'em Sari,et al.  On the Synchrotron Self-Compton Emission from Relativistic Shocks and Its Implications for Gamma-Ray Burst Afterglows , 2000, astro-ph/0005253.

[28]  Tsvi Piran,et al.  Jets in Gamma-Ray Bursts , 1999 .

[29]  Jr.,et al.  STAR FORMATION IN GALAXIES ALONG THE HUBBLE SEQUENCE , 1998, astro-ph/9807187.

[30]  D. Schlegel,et al.  Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds , 1998 .

[31]  T. Piran,et al.  Spectra and Light Curves of Gamma-Ray Burst Afterglows , 1997, astro-ph/9712005.

[32]  C. Kouveliotou,et al.  Identification of two classes of gamma-ray bursts , 1993 .

[33]  J. Dickey,et al.  H I in the Galaxy , 1990 .

[34]  G. Abell,et al.  A Catalog of Rich Clusters of Galaxies , 1989 .