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arXiv 0809.2132astro-ph
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伽玛暴中谱滞后演化与瞬发光辐射的相关性?

A Correlation of Spectral Lag Evolution with Prompt Optical Emission in GRBs?

Michael Stamatikos, Tilan N. Ukwatta, Takanori Sakamoto, Kalvir S. Dhuga

摘要:

我们报告的相关行为之间的即时伽玛射线和光辐射的GRB 080319 B,这(i)强烈建议,它们发生在同一天体物理源区和(ii)表明,它们各自的辐射机制最有可能是动态耦合的观察。我们的初步结果,基于一个新的交叉关联函数(CCF)的方法来确定的时间分辨光谱滞后,总结如下。首先,在Swift-BAT 15-25 keV和50-100 keV能带之间的瞬发伽马射线光子计数的到达偏移的演变(固有的伽马射线光谱滞后)似乎与即时15-350 keV伽马射线和TORTORA观察到的光发射之间的到达偏移量反相关(非本征光学/伽马射线光谱滞后),从而有效地将爆发分为两个主要事件在~T+28+/-2秒。第二,瞬发光辐射嵌套在(a)平凡的固有伽马射线光谱滞后的间隔内(~T+12+-2和~T+50+/-2秒),其中(b)光子指数从硬到软演变的不连续性,幂律拟合到15-150 keV Swift-BAT数据(~T+8+/-2和~T+48+/-1秒),这两者都与瞬发光发射的上升(~T+10+/-1秒)和下降(~T+50+/-1秒)相一致。这一潜在的发现,强大的BAT能量通道的启发式排列和不同的时间箱分辨率,提供了第一个观测证据的光谱滞后和冲击动力学之间的隐含联系的背景下,规范火球现象。

英文摘要:

We report on observations of correlated behavior between the prompt gamma-ray and optical emission from GRB 080319B, which (i) strongly suggest that they occurred within the same astrophysical source region and (ii) indicate that their respective radiation mechanisms were most likely dynamically coupled. Our preliminary results, based upon a new cross-correlation function (CCF) methodology for determining the time-resolved spectral lag, are summarized as follows. First, the evolution in the arrival offset of prompt gamma-ray photon counts between Swift-BAT 15-25 keV and 50-100 keV energy bands (intrinsic gamma-ray spectral lag) appears to be anti-correlated with the arrival offset between prompt 15-350 keV gamma-rays and the optical emission observed by TORTORA (extrinsic optical/gamma-ray spectral lag), thus effectively partitioning the burst into two main episodes at ~T+28+/-2 sec. Second, prompt optical emission is nested within intervals of (a) trivial intrinsic gamma-ray spectral lag (~T+12+-2 and ~T+50+/-2 sec) with (b) discontinuities in the hard to soft evolution of the photon index for a power law fit to 15-150 keV Swift-BAT data (~T+8+/-2 and ~T+48+/-1 sec), both of which coincide with the rise (~T+10+/-1 sec) and decline (~T+50+/-1 sec) of prompt optical emission. This potential discovery, robust across heuristic permutations of BAT energy channels and varying temporal bin resolution, provides the first observational evidence for an implicit connection between spectral lag and the dynamics of shocks in the context of canonical fireball phenomenology.

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