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arXiv 1102.1429astro-ph.HE
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大质量黑洞引起的恒星潮汐破裂的射电瞬变

Radio transients from stellar tidal disruption by massive black holes

Dimitrios Giannios, Brian D. Metzger

摘要:

一颗恒星被一个超大质量黑洞潮汐破坏,为我们提供了一个难得的机会,让我们一窥这些原本休眠的野兽。长期以来,人们一直预测,这种破坏将伴随着一种热“耀斑”,由束缚的恒星碎片的吸积提供动力。已经以这种方式在光学、UV和X射线波长处发现了几个候选的破坏。在这里,我们探讨的观测结果,如果一个适度的吸积功率的一部分被引导到一个超相对论流出。我们表明,相对论性喷流减速,由于其与星际介质在亚秒差距的距离从黑洞的相互作用。由反向冲击加速的电子产生的同步辐射产生了明亮的无线电-红外瞬态,在破裂后约1年的时间尺度上达到峰值。前向激波的辐射在峰值之后的几年内都可以被探测到。在较晚的时候,对潮汐扰动候选者进行深射电跟踪观测可以测试相对论喷出物的存在。即将到来的无线电瞬变调查可能会独立发现每年数十至数百次潮汐中断,补充其他波长的搜索。潮汐扰动的非热发射探测了在相对清洁的条件下射流形成的物理过程,其中流动参数是独立约束的。

英文摘要:

The tidal disruption of a star by a supermassive black hole provides us with a rare glimpse of these otherwise dormant beasts. It has long been predicted that the disruption will be accompanied by a thermal `flare', powered by the accretion of bound stellar debris. Several candidate disruptions have been discovered in this manner at optical, UV and X-ray wavelengths. Here we explore the observational consequences if a modest fraction of the accretion power is channeled into an ultra-relativistic outflow. We show that a relativistic jet decelerates due to its interaction with the interstellar medium at sub-parsec distances from the black hole. Synchrotron radiation from electrons accelerated by the reverse shock powers a bright radio-infrared transient that peaks on a timescale ~1 yr after disruption. Emission from the forward shock may be detectable for several years after the peak. Deep radio follow-up observations of tidal disruption candidates at late times can test for the presence of relativistic ejecta. Upcoming radio transient surveys may independently discover tens to hundreds of tidal disruptions per year, complimenting searches at other wavelengths. Non-thermal emission from tidal disruption probes the physics of jet formation under relatively clean conditions, in which the flow parameters are independently constrained.

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