Low-Luminosity GRB 060218: A Collapsar Jet from a Neutron Star, Leaving a Magnetar as a Remnant?
Low-Luminosity GRB 060218: A Collapsar Jet from a Neutron Star, Leaving a Magnetar as a Remnant?
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DOI：
10.1086/512481
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发表时间：
2006-10
期刊：
影响因子：
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通讯作者：
K. Toma;K. Ioka;T. Sakamoto;Takashi Nakamura
中科院分区：
文献类型：
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作者：
K. Toma;K. Ioka;T. Sakamoto;Takashi Nakamura
伽马射线暴（GRB）060218的亮度比典型的长伽马射线暴低约105倍，与超新星（SN）有关。射电余辉显示没有喷流中断，所以这个爆发可能是由SN激波扫过恒星表面产生的温和的相对论性球形外流引起的。由于这个模型在能量上是困难的，我们建议无线电余辉是由最初准直流出（喷流）的非相对论性相位产生的。我们的喷流模型是由SN分量中的光学线性偏振检测支持的。我们还分析表明，喷流可以穿透祖星星。我们分析了这次爆发的瞬发观测资料，得到了一条光滑的幂律光变曲线，其持续时间可能超过106 s。这种行为与典型伽玛暴X射线耀斑的长时间间歇活动形成对比，这意味着这种爆发的中心引擎与典型伽玛暴不同。这个论点与对这次爆发的SN分量的分析是一致的，这表明祖先星星的质量较小，坍缩为中子星星而不是黑洞。据估计，这种低亮度伽玛暴的准直校正事件率比典型的长伽玛暴高约10倍，并且它们可能形成不同的伽玛暴群：低亮度伽玛暴是由大质量恒星坍缩时来自中子星的轻度相对论性喷流产生的，而典型的长伽玛暴是由来自黑洞的高度相对论性喷流产生的。我们认为GR B 060218的中心发动机是一颗初自转周期P0 ~ 10 ms，磁场B ~ 1016 G的脉冲星（或磁星）。将来可能会观测到磁星的巨大耀斑。
The gamma-ray burst (GRB) 060218 has a luminosity ~105 times lower than that of typical long GRBs and is associated with a supernova (SN). The radio afterglow displays no jet break, so this burst might arise from a mildly relativistic spherical outflow produced by the SN shock sweeping the stellar surface. Since this model is energetically difficult, we propose that the radio afterglow is produced by a nonrelativistic phase of an initially collimated outflow (jet). Our jet model is supported by the detection of optical linear polarization in the SN component. We also show analytically that the jet can penetrate a progenitor star. We analyzed the observational data of the prompt emission of this burst and obtained a smooth power-law light curve which might last longer than 106 s. This behavior contrasts with the long intermittent activities of the X-ray flares of typical GRBs, implying that the central engine of this burst is different from those of typical GRBs. This argument is consistent with the analysis of the SN component of this burst, which suggests that the progenitor star was less massive and collapsed to a neutron star instead of a black hole. The collimation-corrected event rate of such low-luminosity GRBs is estimated to be ~10 times higher than that of typical long GRBs, and they might form a different GRB population: low-luminosity GRBs are produced by mildly relativistic jets from neutron stars at the collapses of massive stars, while typical long GRBs are produced by highly relativistic jets from black holes. We suggest that the central engine of GRB 060218 is a pulsar (or a magnetar) with initial rotation period P0 ~ 10 ms and magnetic field B ~ 1016 G. A giant flare from the magnetar might be observed in future.