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arXiv 1903.09147astro-ph.HEgr-qc
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旋转黑洞引起的潮汐扰动:自旋和碰撞参量的影响

Tidal disruptions by rotating black holes: effects of spin and impact parameter

Emanuel Gafton, Stephan Rosswog

摘要:

我们提出的结果的相对论平滑粒子流体动力学模拟恒星的潮汐破裂旋转超大质量黑洞,为广泛的碰撞参量和黑洞自旋。对于深碰撞,我们发现:相对论性岁差产生的碎片几何形状是用牛顿方程无法得到的;部分流体可以在俯冲轨道上发射,从而降低回退率和所产生的吸积盘的质量;近心点处的多次挤压和反弹可能产生由相关激波爆发产生的独特X射线特征;如果角动量扩散将部分碎片发射到非倾入轨道上,则在边缘半径范围内可能发生中断。也许令人惊讶的是,我们还发现相对论效应在部分破坏中很重要,在部分破坏中,自引力和潮汐力之间的平衡是如此不稳定,以至于其他微小的相对论效应可以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,但相对论效应是温和的,差异在于回落率的温和上升,更晚更小的峰值,以及更长的返回时间。然而,相对论性进动总是会导致较厚的碎片流,无论是在绑定部分(加速循环)和未绑定部分(加速和增强单独的瞬态生产)。我们讨论了各种属性的破坏(压缩在近拱点,形状和传播的能量分布)和潜在的观测值(峰值回落率,上升和衰减的时间,持续时间的超级爱丁顿回落)作为一个函数的碰撞参量和黑洞自旋。

英文摘要:

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.

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