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arXiv 0712.1841astro-ph
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伽玛暴内引擎的三阶段模型:瞬发和早余辉

A three stage model for the inner engine of GRBs: Prompt emission and early afterglow

Jan Staff, Brian Niebergal, Rachid Ouyed

摘要:

我们描述了一个模型内的“夸克新星”方案来解释最近的观测早期X射线余辉的长伽马射线暴(GRB)与雨燕卫星。这是一个在核心坍缩超新星背景下的三阶段模型。阶段1是一个吸积(原)中子星,导致核心坍塌和伽玛暴之间可能存在延迟。第二阶段是吸积到夸克星上,发射一个超相对论喷流,产生即时伽玛暴。当射流与周围介质相互作用产生外部冲击时,这种射流也会产生余辉。从夸克星(在吸积过程中)喷出的较慢的壳层可以重新激发外部冲击,导致X射线余辉中的平坦部分。第三阶段,只有当夸克星坍缩形成黑洞时才会发生,由一个吸积黑洞组成。在这个吸积过程中发射的喷流与前面的夸克星喷流相互作用,并可能产生在早期X射线余辉中经常看到的耀斑活动。或者,如果夸克星没有坍缩成黑洞,我们的模型中也会出现阶段2b。在这种情况下,夸克星可以由于磁制动而自旋下降,并且自旋下降的能量也可能导致X射线余辉的平坦化。除了新发现的早期X射线余辉特征外,这个模型似乎可以解释伽玛暴的能量和时间尺度。

英文摘要:

We describe a model within the ``Quark-nova'' scenario to interpret the recent observations of early X-ray afterglows of long Gamma-Ray Bursts (GRB) with the Swift satellite. This is a three-stage model within the context of a core-collapse supernova. STAGE 1 is an accreting (proto-) neutron star leading to a possible delay between the core collapse and the GRB. STAGE 2 is accretion onto a quark-star, launching an ultrarelativistic jet generating the prompt GRB. This jet also creates the afterglow as the jet interacts with the surrounding medium creating an external shock. Slower shells ejected from the quark star (during accretion), can re-energize the external shock leading to a flatter segment in the X-ray afterglow. STAGE 3, which occurs only if the quark-star collapses to form a black-hole, consists of an accreting black-hole. The jet launched in this accretion process interacts with the preceding quark star jet, and could generate the flaring activity frequently seen in early X-ray afterglows. Alternatively, a STAGE 2b can occur in our model if the quark star does not collapse to a black hole. The quark star in this case can then spin down due to magnetic braking, and the spin down energy may lead to flattening in the X-ray afterglow as well. This model seems to account for both the energies and the timescales of GRBs, in addition to the newly discovered early X-ray afterglow features.

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