DISCERNING THE PHYSICAL ORIGINS OF COSMOLOGICAL GAMMA-RAY BURSTS BASED ON MULTIPLE OBSERVATIONAL CRITERIA: THE CASES OF z = 6.7 GRB 080913, z = 8.2 GRB 090423, AND SOME SHORT/HARD GRBs
DISCERNING THE PHYSICAL ORIGINS OF COSMOLOGICAL GAMMA-RAY BURSTS BASED ON MULTIPLE OBSERVATIONAL CRITERIA: THE CASES OF z = 6.7 GRB 080913, z = 8.2 GRB 090423, AND SOME SHORT/HARD GRBs
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DOI：
10.1088/0004-637x/703/2/1696
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
Bing Zhang;Bin-Bin Zhang-Bin;F. Virgili;E. Liang;D. A. Kann;Xuefeng Wu;D. Proga;Houjun Lv;K. Toma-K.
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作者：
Bing Zhang;Bin-Bin Zhang-Bin;F. Virgili;E. Liang;D. A. Kann;Xuefeng Wu;D. Proga;Houjun Lv;K. Toma-K.
SWIFT最近探测到的两个高红移伽马射线暴，分别是z=6.7时的伽马射线暴080913和z=8.2时的伽马射线暴090423，看起来是本质上短而硬的伽马射线暴。如果它们发生在z⩽1上，它们可能已经被BATSE识别为短/硬伽玛暴。为了解决它们的物理起源，我们对两种物理上不同的类型(类型I/II)的宇宙伽玛暴及其观测特征进行了更深入的研究。我们重申了第I/II型伽玛暴的定义，然后回顾了下列观测标准及其物理动机：超新星(SN)关联、宿主星系的比恒星形成率(SFR)、位置偏移、持续时间、硬度、光谱滞后、统计关联、能量学和准直、余辉性质、红移分布、光度函数和引力波特征。与根据伽马射线属性(持续时间、硬度和光谱滞后)来指定物理类别的传统方法相反，我们采用了另一种方法来定义类型I和类型II的金样品，使用与伽玛射线前身更直接相关的几个标准(SN组合、宿主星系类型和特定的SFR)。然后，我们研究了这两种金样的性质，并与传统的长/软和短/硬样品进行了比较。我们发现，第二类黄金样本合理地跟踪了长/软人口，尽管它包括几个本质上短的(在其余框架中比1 S短)伽玛暴。第一类黄金样品只有五个伽玛暴，其中四个严格来说不是很短，但有延长的发射。在斯威夫特时代探测到的其他短/硬伽玛暴很好地代表了巴斯特短/硬样本，但尚不清楚它们是否都属于I型。我们认为，一些(甚至大多数)高亮度短/硬伽玛暴反而属于II型。根据多种观测标准，我们认为伽玛暴080913和090423更有可能是II型事件。总的来说，我们承认，辨别伽玛暴的物理类别并不总是一目了然，并再次强调援引多种观测标准的重要性。我们谨慎地提出了一种操作程序，用现有的多种观测标准来推断给定伽玛暴的物理起源，并列出了各种警告。
The two high-redshift gamma-ray bursts, GRB 080913 at z = 6.7 and GRB 090423 at z = 8.2, recently detected by Swift appear as intrinsically short, hard GRBs. They could have been recognized by BATSE as short/hard GRBs should they have occurred at z ⩽ 1. In order to address their physical origin, we perform a more thorough investigation on two physically distinct types (Type I/II) of cosmological GRBs and their observational characteristics. We reiterate the definitions of Type I/II GRBs and then review the following observational criteria and their physical motivations: supernova (SN) association, specific star-forming rate (SFR) of the host galaxy, location offset, duration, hardness, spectral lag, statistical correlations, energetics and collimation, afterglow properties, redshift distribution, luminosity function, and gravitational wave signature. Contrary to the traditional approach of assigning the physical category based on the gamma-ray properties (duration, hardness, and spectral lag), we take an alternative approach to define the Type I and Type II Gold Samples using several criteria that are more directly related to the GRB progenitors (SN association, host galaxy type, and specific SFR). We then study the properties of the two Gold Samples and compare them with the traditional long/soft and short/hard samples. We find that the Type II Gold Sample reasonably tracks the long/soft population, although it includes several intrinsically short (shorter than 1 s in the rest frame) GRBs. The Type I Gold Sample only has five GRBs, four of which are not strictly short but have extended emission. Other short/hard GRBs detected in the Swift era represent the BATSE short/hard sample well, but it is unclear whether all of them belong to Type I. We suggest that some (probably even most) high-luminosity short/hard GRBs instead belong to Type II. Based on multiple observational criteria, we suggest that GRB 080913 and GRB 090423 are more likely Type II events. In general, we acknowledge that it is not always straightforward to discern the physical categories of GRBs, and re-emphasize the importance of invoking multiple observational criteria. We cautiously propose an operational procedure to infer the physical origin of a given GRB with available multiple observational criteria, with various caveats laid out.