Delayed Jet Breakouts from Binary Neutron Star Mergers
Delayed Jet Breakouts from Binary Neutron Star Mergers
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DOI：
10.3847/2041-8213/aae51b
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发表时间：
2018-09
期刊：
影响因子：
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通讯作者：
T. Matsumoto;S. Kimura
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文献类型：
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作者：
T. Matsumoto;S. Kimura
短伽玛射线暴（sGRB）被认为是由双中子星星合并产生的。虽然sGRB需要一个相对论射流来打破喷出物，但射流可能会被阻塞，无法产生成功的sGRB。我们提出了一个“延迟突破”的情况下，一个较晚的时间喷气发动机的长期活动可以穿透喷出物，即使即时喷气被窒息。从观测上看，这种晚期喷流是由sGRB中持久的高能发射支持的。解决喷射物中的射流传播，我们表明，一个典型的后期活动很容易实现延迟突破。这一事件显示的不是瞬发γ射线，而是长时间的X射线发射，持续时间为102-3 s，甚至104-5 s。一些延迟事件可能已经被探测为没有超新星特征的软长伽玛暴。在乐观的情况下，第二代引力波探测器每年都会探测到一些与引力波（GW）重合的事件。没有γ射线的合并事件的X射线跟踪将是对二元合并中持久发动机活动的探索。
Short gamma-ray bursts (sGRBs) are thought to be produced by binary neutron star mergers. While an sGRB requires a relativistic jet to break out of ejecta, the jet may be choked and fails to produce a successful sGRB. We propose a “delayed breakout” scenario where a late-time jet launched by a long-term engine activity can penetrate ejecta even if a prompt jet is choked. Observationally, such a late-time jet is supported by the long-lasting high-energy emissions in sGRBs. Solving the jet propagation in ejecta, we show that a typical late-time activity easily achieves the delayed breakout. This event shows not prompt γ-rays but long-time X-ray emissions for ∼102–3 s or even ∼104–5 s. Some delayed events may be already detected as soft-long GRBs without supernova signatures. In an optimistic case, a few events coincident with gravitational-waves (GWs) are detected by the second-generation GW detectors every year. X-ray follow-ups of merger events without γ-rays will be a probe of long-lasting engine activities in binary mergers.