Hyperaccretion after the Blandford-Znajek Process: A New Model for GRBs with X-Ray Flares Observed in Early Afterglows
Hyperaccretion after the Blandford-Znajek Process: A New Model for GRBs with X-Ray Flares Observed in Early Afterglows
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DOI：
10.1088/1009-9271/8/4/04
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
W. Lei;Ding-xiong Wang;Y. Zou;Lei Zhang
中科院分区：
文献类型：
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作者：
W. Lei;Ding-xiong Wang;Y. Zou;Lei Zhang
本文提出了一个包含Blandford-Znajek（BZ）和超吸积过程的三阶段模型来解释最近观测到的伽玛射线暴早期余辉。在第一阶段，提示伽玛暴是由一个旋转的黑洞（BH）调用BZ过程。第二阶段是安静阶段，BZ过程被关闭，并且BH上的吸积被磁耦合（MC）过程施加的扭矩抑制。通过MC过程从BH传输的部分旋转能量作为磁能存储在磁盘中。在第三阶段，当磁盘中的磁能积累并触发磁不稳定性时，MC过程被关闭。在这一刻，超吸积过程可能开始，在这个重新启动的中央引擎中发射的喷流产生了观察到的X射线耀斑。这个模型可以解释早期余辉中观测到的X射线耀斑的伽玛暴的能量和时间尺度。
We propose a three-stage model with Blandford-Znajek (BZ) and hyperaccretion process to interpret the recent observations of early afterglows of Gamma-Ray Bursts (GRBs). In the first stage, the prompt GRB is powered by a rotating black hole (BH) invoking the BZ process. The second stage is a quiet stage, in which the BZ process is shut off, and the accretion onto the BH is depressed by the torque exerted by the magnetic coupling (MC) process. Part of the rotational energy transported by the MC process from the BH is stored in the disk as magnetic energy. In the third stage, the MC process is shut off when the magnetic energy in the disk accumulates and triggers magnetic instability. At this moment, the hyperaccretion process may set in, and the jet launched in this restarted central engine generates the observed X-ray flares. This model can account for the energies and timescales of GRBs with X-ray flares observed in early afterglows.