Tidal disruptions by rotating black holes: effects of spin and impact parameter
Tidal disruptions by rotating black holes: effects of spin and impact parameter
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旋转黑洞造成的潮汐破坏：自旋和撞击参数的影响
DOI：
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发表时间：
2019
影响因子：
4.8
通讯作者：
S. Rosswog
中科院分区：
文献类型：
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作者：
E. Gafton;S. Rosswog
我们提出了通过旋转超大质量黑洞对恒星潮汐破坏进行相对论平滑粒子流体动力学模拟的结果，适用于各种撞击参数和黑洞自旋。对于深度接触，我们发现： 相对论进动产生了牛顿方程无法获得的碎片几何形状；部分流体可以发射到暴跌轨道上，从而降低回落率和由此产生的吸积盘的质量；近点处的多次挤压和弹跳可能会因相关的激波爆发而产生独特的 X 射线特征；如果角动量扩散将部分碎片发射到非坠落轨道上，则在边界半径内可能会发生破坏。也许令人惊讶的是，我们还发现相对论效应在部分扰动中很重要，在部分扰动中，自引力和潮汐力之间的平衡是如此不稳定，以至于微小的相对论效应可能对恒星的命运产生决定性的影响。在这两者之间，恒星被完全破坏，但相对论效应轻微，差异在于回落率上升较平缓，峰值较晚且较小，以及返回时间较长。然而，相对论进动总是会导致更厚的碎片流，无论是在束缚部分（加速环化）还是在未束缚部分（加速和增强单独瞬变的产生）。我们讨论了破坏的各种特性（近点处的压缩、能量分布的形状和扩散）和潜在的可观测值（峰值回落率、上升和衰减时间、超爱丁顿回落的持续时间）作为撞击参数和黑洞自旋的函数。
We present the results of relativistic smoothed particle hydrodynamics simulations of tidal disruptions of stars by rotating supermassive black holes, for a wide range of impact parameters and black hole spins. For deep encounters, we find that: relativistic precession creates debris geometries impossible to obtain with the Newtonian equations; part of the fluid can be launched on plunging orbits, reducing the fallback rate and the mass of the resulting accretion disc; multiple squeezings and bounces at periapsis may generate distinctive X-ray signatures resulting from the associated shock breakout; disruptions can occur inside the marginally bound radius, if the angular momentum spread launches part of the debris on non-plunging orbits. Perhaps surprisingly, we also find relativistic effects important in partial disruptions, where the balance between self-gravity and tidal forces is so precarious that otherwise minor relativistic effects can have decisive consequences on the stellar fate. In between, where the star is fully disrupted but relativistic effects are mild, the difference resides in a gentler rise of the fallback rate, a later and smaller peak, and longer return times. However, relativistic precession always causes thicker debris streams, both in the bound part (speeding up circularization) and in the unbound part (accelerating and enhancing the production of separate transients). We discuss various properties of the disruption (compression at periapsis, shape and spread of the energy distribution) and potential observables (peak fallback rate, times of rise and decay, duration of super-Eddington fallback) as a function of the impact parameter and the black hole spin.