Margutti R, Metzger B D, Chornock R, Milisavljevic D, Berger E, Blanchard P K, Guidorzi C, Migliori G, Kamble A, Lunnan R, Nicholl M, Coppejans D L, Dall'Osso S, Drout M R, Perna R, Sbarufatti B
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA.
Center for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, NY 10003, USA.
Astrophys J. 2017 Feb 10;836(1). doi: 10.3847/1538-4357/836/1/25. Epub 2017 Feb 6.
We present the detection of persistent soft X-ray radiation with ~ 10-10 erg s at the location of the extremely luminous, double-humped transient ASASSN-15lh as revealed by and . We interpret this finding in the context of observations from our multiwavelength campaign, which revealed the presence of weak narrow nebular emission features from the host-galaxy nucleus and clear differences with respect to superluminous supernova optical spectra. Significant UV flux variability on short timescales detected at the time of the rebrightening disfavors the shock interaction scenario as the source of energy powering the long-lived UV emission, while deep radio limits exclude the presence of relativistic jets propagating into a low-density environment. We propose a model where the extreme luminosity and double-peaked temporal structure of ASASSN-15lh is powered by a central source of ionizing radiation that produces a sudden change in the ejecta opacity at later times. As a result, UV radiation can more easily escape, producing the second bump in the light curve. We discuss different interpretations for the intrinsic nature of the ionizing source. We conclude that, the X-ray source is physically associated with the optical-UV transient, then ASASSN-15lh most likely represents the tidal disruption of a main-sequence star by the most massive spinning black hole detected to date. In this case, ASASSN-15lh and similar events discovered in the future would constitute the most direct probes of very massive, dormant, spinning, supermassive black holes in galaxies. Future monitoring of the X-rays may allow us to distinguish between the supernova hypothesis and the hypothesis of a tidal disruption event.
我们展示了在极亮的双峰瞬变天体ASASSN - 15lh位置探测到持续的软X射线辐射，其通量约为10^-10尔格/秒，这是由[相关文献1]和[相关文献2]揭示的。我们在多波段观测活动的背景下解释这一发现，该活动揭示了宿主星系核存在微弱的窄星云发射特征，并且与超亮超新星的光学光谱存在明显差异。在亮度重新增强时检测到的短时间尺度上显著的紫外通量变化不支持激波相互作用情景作为为长期紫外发射提供能量的来源，而深度射电观测限制排除了相对论性喷流在低密度环境中传播的可能性。我们提出一个模型，其中ASASSN - 15lh的极端亮度和双峰时间结构由一个电离辐射的中心源提供能量，该源在后期使抛射物质的不透明度发生突然变化。结果，紫外辐射能够更容易地逃逸，在光变曲线中产生第二个峰值。我们讨论了对电离源内在性质的不同解释。我们得出结论，如果X射线源与光学 - 紫外瞬变天体在物理上相关联，那么ASASSN - 15lh最有可能代表一颗主序星被迄今为止探测到的最大质量的旋转黑洞潮汐瓦解。在这种情况下，ASASSN - 15lh以及未来发现的类似事件将构成对星系中非常大质量、休眠、旋转的超大质量黑洞最直接的探测。未来对X射线的监测可能使我们能够区分超新星假设和潮汐瓦解事件假设。
