On the Investigation of the Closure Relations for Gamma-Ray Bursts Observed by Swift in the Post-plateau Phase and the GRB Fundamental Plane
On the Investigation of the Closure Relations for Gamma-Ray Bursts Observed by Swift in the Post-plateau Phase and the GRB Fundamental Plane
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DOI：
10.3847/1538-4357/abb702
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发表时间：
2020-09
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影响因子：
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通讯作者：
G. Srinivasaragavan;M. Dainotti;N. Fraija;Xavier Hernandez;S. Nagataki;A. Lenart;L. Bowden;Robert Wagner
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文献类型：
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作者：
G. Srinivasaragavan;M. Dainotti;N. Fraija;Xavier Hernandez;S. Nagataki;A. Lenart;L. Bowden;Robert Wagner
伽玛射线暴（GRB）是宇宙大爆炸之后最具爆炸性的现象。大部分伽玛射线暴光变曲线（LC）显示X射线平台。我们对Neil Gehrels Swift天文台从发射到2019年8月观测到的所有GRB（具有已知和未知的红移）进行了最全面的分析。我们拟合了455个LC，显示出一个平台，并探讨这些LC是否遵循闭合关系，余辉的时间和光谱指数之间的关系，对应于两个不同的天体物理环境和外部前向激波（ES）模型内的冷却制度，并发现ES模型适用于大多数情况。最有利的环境是恒定密度的星际或缓慢冷却的风介质。我们还证实了存在的基本平面之间的关系的静止帧的时间和光度在平台发射和峰值即时光度为这个放大的样品的结束，并测试这种关系组对应于我们已知的红移样品的天体物理环境。该平面在最佳拟合参数和色散方面成为与这些环境相对应的关键判别式。大多数满足天体物理环境闭合关系的伽玛暴的内禀散射σ与“黄金”伽玛暴的内禀散射σ在1σ以内，“黄金”伽玛暴是长伽玛暴的一个子集，具有相对平坦的平台。我们还发现，伽玛暴满足封闭关系，表明一个快速冷却制度有一个较低的σ比以往文献中发现的。
Gamma-ray Bursts (GRBs) are the most explosive phenomena in the universe after the big bang. A large fraction of GRB lightcurves (LCs) shows X-ray plateaus. We perform the most comprehensive analysis of all GRBs (with known and unknown redshifts) with plateau emission observed by The Neil Gehrels Swift Observatory from its launch until 2019 August. We fit 455 LCs showing a plateau and explore whether these LCs follow closure relations, relations between the temporal and spectral indices of the afterglow, corresponding to two distinct astrophysical environments and cooling regimes within the external forward shock (ES) model, and find that the ES model works for the majority of cases. The most favored environments are a constant-density interstellar or wind medium with slow cooling. We also confirm the existence of the fundamental plane relation between the rest-frame time and luminosity at the end of the plateau emission and the peak prompt luminosity for this enlarged sample, and test this relation on groups corresponding to the astrophysical environments of our known redshift sample. The plane becomes a crucial discriminant corresponding to these environments in terms of the best-fitting parameters and dispersions. Most GRBs for which the closure relations are fulfilled with respect to astrophysical environments have an intrinsic scatter σ compatible within 1σ of that of the “Gold” GRBs, a subset of long GRBs with relatively flat plateaus. We also find that GRBs satisfying closure relations indicating a fast cooling regime have a lower σ than ever previously found in literature.