The Giant X-Ray Flare of GRB 050502B: Evidence for Late-Time Internal Engine Activity
The Giant X-Ray Flare of GRB 050502B: Evidence for Late-Time Internal Engine Activity
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DOI：
10.1086/500655
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发表时间：
2005-12
期刊：
影响因子：
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通讯作者：
A. Falcone;D. Burrows;D. Lazzati;S. Campana;S. Kobayashi;Bing Zhang;P. Mészáros;K. Page;J. Ken
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文献类型：
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作者：
A. Falcone;D. Burrows;D. Lazzati;S. Campana;S. Kobayashi;Bing Zhang;P. Mészáros;K. Page;J. Ken
直到最近，伽玛射线暴（GRBs）余辉中的x射线耀斑是一种很少被探测到的现象；因此，它们的性质是不清楚的。在GRB 050502B的余辉期间，有记录以来最大的x射线耀斑迅速上升到雨燕x射线望远镜探测到的余辉光曲线上方。耀斑的峰值通量是下伏余辉的500倍，发生在标称提示爆发发射后12分钟。该x射线耀斑在0.2-10.0 keV波段的影响为（1.0±0.05）× 10-6 ergs cm-2，超过了标称提示爆发的影响。耀斑期间的光谱比耀斑前后测量的光谱要硬得多。后来，在潜在的余辉上方检测到额外的通量增加，以及余辉光曲线的中断。下面所有的证据，包括光谱，特别是在巨大耀斑期间和周围的时间信息，都表明这个巨大的耀斑是由于中央发动机活动后期导致的内部能量耗散的结果，而不是与余辉有关的影响。我们还发现，这些数据与第二次中央引擎活动事件是一致的，在这个事件中，喷射物的移动速度比第一次慢，造成了巨大的耀斑，然后继续超越并刷新了余辉激波，从而在光曲线的更晚时间造成了额外的活动。
Until recently, X-ray flares during the afterglow of gamma-ray bursts (GRBs) were a rarely detected phenomenon; thus, their nature is unclear. During the afterglow of GRB 050502B, the largest X-ray flare ever recorded rose rapidly above the afterglow light curve detected by the Swift X-Ray Telescope. The peak flux of the flare was >500 times that of the underlying afterglow, and it occurred >12 minutes after the nominal prompt burst emission. The fluence of this X-ray flare, (1.0 ± 0.05) × 10-6 ergs cm-2 in the 0.2-10.0 keV energy band, exceeded the fluence of the nominal prompt burst. The spectra during the flare were significantly harder than those measured before and after the flare. Later in time, there were additional flux increases detected above the underlying afterglow, as well as a break in the afterglow light curve. All evidence presented below, including spectral and, particularly, timing information during and around the giant flare, suggests that this giant flare was the result of internal dissipation of energy due to late central engine activity, rather than an afterglow-related effect. We also find that the data are consistent with a second central engine activity episode, in which the ejecta is moving slower than that of the initial episode, causing the giant flare and then proceeding to overtake and refresh the afterglow shock, thus causing additional activity at even later times in the light curve.