Bimodal Long-lasting Components in Short Gamma-Ray Bursts: Promising Electromagnetic Counterparts to Neutron Star Binary Mergers
Bimodal Long-lasting Components in Short Gamma-Ray Bursts: Promising Electromagnetic Counterparts to Neutron Star Binary Mergers
复制标题
DOI：
10.3847/1538-4357/aa8775
复制
发表时间：
2017-07
期刊：
影响因子：
--
通讯作者：
S. Kisaka;K. Ioka;T. Sakamoto
中科院分区：
文献类型：
--
作者：
S. Kisaka;K. Ioka;T. Sakamoto
短伽玛射线暴（GRB）的长时间持续发射对于揭示中心引擎的物理起源以及探测来自中子星星双星合并的引力波（GW）的电磁（EM）对应物至关重要。我们调查了65短伽玛暴的X射线光变曲线，这是以前的研究的6倍多，结合Swift/BAT和XRT数据。光变曲线在>5σ处由两个不同的分量组成，具有亮度和持续时间的双峰分布，即延长（时间刻度为10103秒）和平台排放（时间刻度为10103秒），这可能是发动机的主要活动，但不是余辉。扩展发射具有与瞬时发射相当的各向同性能量，而平台发射具有该能量的1.01 -1倍。我们的样本中有一半（50%）具有这两种成分，而另一半则与具有这两种成分一致。这使我们推测，几乎所有的短伽玛暴都有扩展和平台发射。这种持久的发射可以用黑洞喷出的喷射物来解释，并且可以为GRB 130603 B和GRB 160821 B等macronovae（或kilonovae）提供动力。基于所观察到的特性，我们量化了电磁对应物对GW的可探测性，包括散射到离轴角的平台发射，CALET/HXM，INTEGRAL/SPI-ACS，Fermi/GBM，MAXI/GSC，Swift/BAT，XRT，未来的ISS-龙虾/WFI，Einstein Probe/WXT和eROSITA。
Long-lasting emission of short gamma-ray bursts (GRBs) is crucial to reveal the physical origin of the central engine as well as to detect electromagnetic (EM) counterparts to gravitational waves (GWs) from neutron star binary mergers. We investigate 65 X-ray light curves of short GRBs, which is six times more than previous studies, by combining both Swift/BAT and XRT data. The light curves are found to consist of two distinct components at >5σ with bimodal distributions of luminosity and duration, i.e., extended (with a timescale of ≲103 s) and plateau emission (with a timescale of ≳103 s), which are likely the central engine activities, but not afterglows. The extended emission has an isotropic energy comparable to the prompt emission, while the plateau emission has ∼0.01–1 times this energy. Half (50%) of our sample has both components, while the other half is consistent with having both components. This leads us to conjecture that almost all short GRBs have both the extended and plateau emission. The long-lasting emission can be explained by the jets from black holes with fallback ejecta, and could power macronovae (or kilonovae) like GRB 130603B and GRB 160821B. Based on the observed properties, we quantify the detectability of EM counterparts to GWs, including the plateau emission scattered to the off-axis angle, with CALET/HXM, INTEGRAL/SPI-ACS, Fermi/GBM, MAXI/GSC, Swift/BAT, XRT, the future ISS-Lobster/WFI, Einstein Probe/WXT, and eROSITA.