Barthelmy S D, Chincarini G, Burrows D N, Gehrels N, Covino S, Moretti A, Romano P, O'Brien P T, Sarazin C L, Kouveliotou C, Goad M, Vaughan S, Tagliaferri G, Zhang B, Antonelli L A, Campana S, Cummings J R, D'Avanzo P, Davies M B, Giommi P, Grupe D, Kaneko Y, Kennea J A, King A, Kobayashi S, Melandri A, Meszaros P, Nousek J A, Patel S, Sakamoto T, Wijers R A M J
NASA/Goddard Space Flight Center Greenbelt, Maryland 20771, USA.
Nature. 2005 Dec 15;438(7070):994-6. doi: 10.1038/nature04392.
Two short (< 2 s) gamma-ray bursts (GRBs) have recently been localized and fading afterglow counterparts detected. The combination of these two results left unclear the nature of the host galaxies of the bursts, because one was a star-forming dwarf, while the other was probably an elliptical galaxy. Here we report the X-ray localization of a short burst (GRB 050724) with unusual gamma-ray and X-ray properties. The X-ray afterglow lies off the centre of an elliptical galaxy at a redshift of z = 0.258 (ref. 5), coincident with the position determined by ground-based optical and radio observations. The low level of star formation typical for elliptical galaxies makes it unlikely that the burst originated in a supernova explosion. A supernova origin was also ruled out for GRB 050709 (refs 3, 31), even though that burst took place in a galaxy with current star formation. The isotropic energy for the short bursts is 2-3 orders of magnitude lower than that for the long bursts. Our results therefore suggest that an alternative source of bursts--the coalescence of binary systems of neutron stars or a neutron star-black hole pair--are the progenitors of short bursts.
最近，两个短伽马射线暴（GRBs，持续时间<2秒）已被定位，并且检测到了逐渐衰减的余辉对应体。这两个结果结合起来，使得暴发源宿主星系的性质仍不明确，因为其中一个宿主星系是正在形成恒星的矮星系，而另一个可能是椭圆星系。在此，我们报告了一个具有异常伽马射线和X射线性质的短暴（GRB 050724）的X射线定位。该X射线余辉位于一个红移为z = 0.258的椭圆星系中心之外（参考文献5），与地面光学和射电观测确定的位置一致。椭圆星系典型的低恒星形成水平使得该暴不太可能起源于超新星爆发。对于GRB 050709（参考文献3、31），超新星起源也被排除，尽管该暴发生在一个目前正在形成恒星的星系中。短暴的各向同性能量比长暴低2至3个数量级。因此，我们的结果表明，短暴的另一个来源——中子星双星系统或中子星 - 黑洞对的合并——是短暴的前身。
