GRB 191019A: A Short Gamma-Ray Burst in Disguise from the Disk of an Active Galactic Nucleus
GRB 191019A: A Short Gamma-Ray Burst in Disguise from the Disk of an Active Galactic Nucleus
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DOI：
10.3847/2041-8213/acd18c
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发表时间：
2023-03
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影响因子：
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通讯作者：
D. Lazzati;R. Perna;B. Gompertz;A. Levan
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作者：
D. Lazzati;R. Perna;B. Gompertz;A. Levan
长短伽玛射线暴（GRB），规范上分开在2秒左右的持续时间，与不同的祖先：一个大质量的星星的崩溃和合并的两个紧凑的对象，分别。191019 A是一个长伽玛暴（T90 ~ 64 s）。尽管红移z = 0.248相对较小，并且哈勃太空望远镜进行了后续观测，但没有发现伴随的超新星。此外，宿主星系没有显著的星星形成活动。在这里，我们建议，GRB 191019 A是由一个二进制紧凑合并，其即时发射的时间被拉伸与致密的外部介质的相互作用。这是可以预期的，如果爆发的祖先位于活动星系核的盘中，就像爆炸定位在靠近其宿主星系中心的地方一样。我们发现，GRB 191019 A的光变曲线可以很好地用一个本征持续时间teng = 1.1 s，能量Eiso = 1051 erg的爆发来模拟，这个爆发在密度为107-108 cm−3的介质中适度偏离轴。双峰光变曲线具有高密度介质中伽玛暴预测的特征，其中第一个峰由光球产生，第二个峰由内部冲击发生之前发生的反向冲击的重叠产生。这将使GRB 191019 A成为第一个被证实的来自吸积盘内的恒星爆炸，对吸积流中恒星的形成和演化以及引力波源种群具有重要意义。
Long and short gamma-ray bursts (GRBs), canonically separated at around 2 s duration, are associated with different progenitors: the collapse of a massive star and the merger of two compact objects, respectively. GRB 191019A was a long GRB (T 90 ∼ 64 s). Despite the relatively small redshift z = 0.248 and Hubble Space Telescope follow-up observations, an accompanying supernova was not detected. In addition, the host galaxy did not have significant star formation activity. Here we propose that GRB 191019A was produced by a binary compact merger, whose prompt emission was stretched in time by the interaction with a dense external medium. This would be expected if the burst progenitor was located in the disk of an active galactic nucleus, as supported by the burst localization close to the center of its host galaxy. We show that the light curve of GRB 191019A can be well modeled by a burst of intrinsic duration t eng = 1.1 s and of energy E iso = 1051 erg seen moderately off axis, exploding in a medium of density ∼107–108 cm−3. The double-peaked light curve carries the telltale features predicted for GRBs in high-density media, where the first peak is produced by the photosphere and the second by the overlap of reverse shocks that take place before the internal shocks could happen. This would make GRB 191019A the first confirmed stellar explosion from within an accretion disk, with important implications for the formation and evolution of stars in accretion flows and for gravitational-waves source populations.