原磁星自旋下降产生的短持续时间伽马射线暴
Short Duration Gamma-Ray Bursts with Extended Emission from Proto-Magnetar Spin-Down
摘要：
有越来越多的证据表明，存在一类伽马射线暴（GRB），其特征是在发射开始时出现约0.1-1 s的硬辐射尖峰，然后经过约3-10 s的发射平静期，然后是持续约10-100 s的较软的延长发射期。在少数经过充分研究的情况下，这些“具有扩展发射的短GRB”没有显示出明亮的关联超新星（SN）的证据。我们认为这些事件是由一个高磁化、快速旋转的中子星（一个"原磁星“）的形成和早期演化所产生的，它是由白矮星（WD）的吸积诱导坍缩（AIC）、WD-WD双星的合并和坍缩，或者，可能是双中子星双星的合并所形成的。最初的发射尖峰是由在AIC或合并事件期间形成的小圆盘在原磁星上的吸积提供动力的。扩展发射是由相对论风产生的，它在约10-100 s的时间尺度上提取原磁星的旋转能量。在瞬时发射和扩展发射之间的约3-10秒的延迟是新形成的原磁星充分冷却所需的时间，从而使来自其表面的中微子加热风变得超相对论。由于原磁星很少或没有发射Ni 56（<1 e-3 M_sun），这些事件应该不会产生明亮的SN状瞬变。我们使用冷却原磁星的自旋下降计算来模拟GRB 060614的扩展发射，发现与初始旋转周期为1 ms和表面偶极场为3e 15 G的磁星的观测结果合理一致。如果伽玛暴确实是由AIC或WD-WD合并产生的，它们应该发生在早期和晚期星系的混合物中，并且不应该产生强的引力波发射。我们的模型的一个额外的结果是存在的X射线闪光没有伴随着一个明亮的SN。
英文摘要：
Evidence is growing for a class of gamma-ray bursts (GRBs) characterized by an initial ~0.1-1 s spike of hard radiation followed, after a ~3-10 s lull in emission, by a softer period of extended emission lasting ~10-100 s. In a few well-studied cases, these ``short GRBs with extended emission'' show no evidence for a bright associated supernova (SN). We propose that these events are produced by the formation and early evolution of a highly magnetized, rapidly rotating neutron star (a ``proto-magnetar'') which is formed from the accretion-induced collapse (AIC) of a white dwarf (WD), the merger and collapse of a WD-WD binary, or, perhaps, the merger of a double neutron star binary. The initial emission spike is powered by accretion onto the proto-magnetar from a small disk that is formed during the AIC or merger event. The extended emission is produced by a relativistic wind that extracts the rotational energy of the proto-magnetar on a timescale ~10-100 s. The ~3-10 s delay between the prompt and extended emission is the time required for the newly-formed proto-magnetar to cool sufficiently that the neutrino-heated wind from its surface becomes ultra-relativistic. Because a proto-magnetar ejects little or no Ni56 (< 1e-3 M_sun), these events should not produce a bright SN-like transient. We model the extended emission from GRB060614 using spin-down calculations of a cooling proto-magnetar, finding reasonable agreement with observations for a magnetar with an initial rotation period of ~1 ms and a surface dipole field of ~3e15 G. If GRBs are indeed produced by AIC or WD-WD mergers, they should occur within a mixture of both early and late-type galaxies and should not produce strong gravitational wave emission. An additional consequence of our model is the existence of X-ray flashes unaccompanied by a bright SN.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
