标题： 近拱点后煎饼：潮汐瓦解事件中的自引力补给 显示英文标题

标题： Post-periapsis pancakes: sustenance for self-gravity in tidal disruption events

摘要： 当恒星被一个超大质量黑洞的引力场撕裂时，就会发生潮汐瓦解事件，这一过程会产生一连串碎片，这些碎片的演化最终决定了该事件的观测特性。 我们在此展示，在近日点后焦散现象——即如果气体团块组成的流体仅在黑洞的引力场中演化，则这些气体团块的轨迹会塌缩成二维表面的位置——会在恒星的近日点距离接近黑洞的潮汐半径时出现。 研究表明，这种“煎饼状”结构会在碎片流中诱导显著的密度扰动，而对于更硬的物态方程（绝热指数$\gamma \gtrsim 5/3$），这些波动足以使流体在引力作用下不稳定，从而导致其碎裂成束缚的团块。 我们的研究结果在潮汐瓦解事件的观测特性背景下进行了讨论。 显示英文摘要

摘要： A tidal disruption event, which occurs when a star is destroyed by the gravitational field of a supermassive black hole, produces a stream of debris, the evolution of which ultimately determines the observational properties of the event. Here we show that a post-periapsis caustic -- a location where the locus of gas parcels comprising the stream would collapse into a two-dimensional surface if they evolved solely in the gravitational field of the hole -- occurs when the pericenter distance of the star is on the order of the tidal radius of the hole. It is demonstrated that this "pancake" induces significant density perturbations in the debris stream, and, for stiffer equations of state (adiabatic index $\gamma \gtrsim 5/3$), these fluctuations are sufficient to gravitationally destabilize the stream, resulting in its fragmentation into bound clumps. The results of our findings are discussed in the context of the observational properties of tidal disruption events.