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arXiv 1708.07488astro-ph.HE
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结构喷流的离轴短伽玛暴与GW事件的对应

Off-axis short GRBs from structured jets as counterparts to GW events

Adithan Kathirgamaraju, Rodolfo Barniol Duran, Dimitrios Giannios

摘要:

中子星合并被认为是产生与引力波(GW)相关的电磁(EM)信号的最有利的源。这些合并可能是短时间伽马射线暴(GRB)的前身。超相对论喷流产生短暂的γ射线辐射(即“瞬发γ射线暴”辐射),因此,这种辐射沿喷流在一个小的立体角上强烈地发射。据估计,在LIGO体积内的一个短GRB喷流沿着我们的视线出现之前,需要十年或更长时间。由于这个原因,作为GW事件的EM对应物的提示信号的研究已经稀疏。我们认为,对于一个现实的喷流模型,一个其亮度和洛伦兹因子随角度变化平稳,提示信号可以检测到一个显着更广泛的视角范围。这可能导致一种新型的EM对应物,“离轴”短GRB。我们的估计和模拟表明,即使观察者相对于喷流严重失准,借助LIGO触发器的时间重合来检测这些信号也是可行的。

英文摘要:

Binary neutron star mergers are considered to be the most favorable sources that produce electromagnetic (EM) signals associated with gravitational waves (GWs). These mergers are the likely progenitors of short duration gamma-ray bursts (GRBs). The brief gamma-ray emission (the "prompt GRB" emission) is produced by ultra-relativistic jets, as a result, this emission is strongly beamed over a small solid angle along the jet. It is estimated to be a decade or more before a short GRB jet within the LIGO volume points along our line of sight. For this reason, the study of the prompt signal as an EM counterpart to GW events has been sparse. We argue that for a realistic jet model, one whose luminosity and Lorentz factor vary smoothly with angle, the prompt signal can be detected for a significantly broader range of viewing angles. This can lead to a new type of EM counterpart, an "off-axis" short GRB. Our estimates and simulations show that it is feasible to detect these signals with the aid of the temporal coincidence from a LIGO trigger, even if the observer is substantially misaligned with respect to the jet.

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