Levan 2007 GRB 060912A的长短暴划分

主要内容:
从时标、宿主星系等的观测，发现很难GRB 060912A是长暴还是短暴。

精彩摘抄:


文章信息:
A case of mistaken identity? GRB 060912A and the nature of the long -- short GRB divide

Authors: A.J. Levan, P. Jakobsson, C. Hurkett, N.R. Tanvir, J. Gorosabel, P. Vreeswijk, E. Rol, R. Chapman, N. Gehrels, P.T. O'Brien, J.P. Osborne, R.S. Priddey, C. Kouveliotou, R. Starling, D. Vanden Berk, K. Wiersema

(Submitted on 19 Apr 2007)

Abstract: We investigate the origin of the GRB 060912A, which has observational properties that make its classification as either a long or short burst ambiguous. Short duration GRBs (SGRBs) are thought to have typically lower energies than long duration bursts, can be found in galaxies with populations of all ages and are likely to originate from different progenitors to the long duration bursts. However, it has become clear that duration alone is insufficient to make a distinction between the two populations in many cases, leading to a desire to find additional discriminators of burst type. GRB 060912A had a duration of 6 s and occurred only ~10 arcsec from a bright, low redshift ($z=0.0936$) elliptical galaxy, suggesting that this may have been the host, which would favour it being a short-burst. However, our deep optical imaging and spectroscopy of the location of GRB 060912A using the VLT shows that GRB 060912A more likely originates in a distant star forming galaxy at z=0.937, and is most likely a long burst. This demonstrates the risk in identifying bright, nearby galaxies as the hosts of given GRBs without further supporting evidence. Further, it implies that, in the absence of secure identifications, "host" type, or more broadly discriminators which rely on galaxy redshifts, may not be good indicators of the true nature of any given GRB.

Comments:

9 pages, 5 figures, accepted for publication in MNRAS

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:0704.2525v1 [astro-ph]