RADIAL ANGULAR MOMENTUM TRANSFER AND MAGNETIC BARRIER FOR SHORT-TYPE GAMMA-RAY-BURST CENTRAL ENGINE ACTIVITY
RADIAL ANGULAR MOMENTUM TRANSFER AND MAGNETIC BARRIER FOR SHORT-TYPE GAMMA-RAY-BURST CENTRAL ENGINE ACTIVITY
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DOI：
10.1088/0004-637x/760/1/63
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发表时间：
2012-09
期刊：
影响因子：
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通讯作者：
Tong Liu;E. Liang;Weimin Gu;S. Hou;W. Lei;Lin Lin-Lin;Z. Dai;Shuang-Nan Zhang
中科院分区：
文献类型：
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作者：
Tong Liu;E. Liang;Weimin Gu;S. Hou;W. Lei;Lin Lin-Lin;Z. Dai;Shuang-Nan Zhang
在大约一半的已知短型伽玛射线暴（SGRB）中，Swift/BAT观测到了初始硬尖峰之后长达100 s的软扩展发射（EE）。这挑战了SGRB的传统中心引擎模型，即，紧凑型星星合并模型。在黑洞-中子-恒星合并模型的框架下，我们研究了盘中的径向角动量转移和黑洞周围的磁垒在SGRB中心引擎活动中的作用.我们发现，径向角动量转移可能会显着延长吸积过程的寿命，这可能是由磁垒分为多个情节。基于中微子主导吸积流模型的数值计算表明，盘的质量对产生观测到的EE是至关重要的。当盘的质量为10.8 M时，我们的模型可以在合理的参数设置下再现观测到的主事件和EE事件的时间尺度和光度。当盘的质量为1.02M时，EE分量的预测亮度比观测亮度低约一个数量级，时间尺度小于20 s。在这种情况下，Swift/BAT类仪器可能不够灵敏，无法检测到EE组件。我们认为，EE组件可能是一个探头的合并过程和磁盘形成紧凑的星星合并。
Soft extended emission (EE) following initial hard spikes up to 100 s was observed with Swift/BAT for about half of known short-type gamma-ray bursts (SGRBs). This challenges the conversional central engine models of SGRBs, i.e., compact star merger models. In the framework of black-hole–neutron-star merger models, we study the roles of radial angular momentum transfer in the disk and the magnetic barrier around the black hole in the activity of SGRB central engines. We show that radial angular momentum transfer may significantly prolong the lifetime of the accretion process, which may be divided into multiple episodes by the magnetic barrier. Our numerical calculations based on models of neutrino-dominated accretion flows suggest that disk mass is critical for producing the observed EE. In the case of the mass being ∼0.8 M☉, our model can reproduce the observed timescale and luminosity of both the main and the EE episodes in a reasonable parameter set. The predicted luminosity of the EE component is lower than the observed EE within about one order of magnitude and the timescale is shorter than 20 s if the disk mass is ∼0.2 M☉. Swift/BAT-like instruments may be not sensitive enough to detect the EE component in this case. We argue that the EE component could be a probe for the merger process and disk formation for compact star mergers.