arXiv 2302.006072023-02-01astro-ph.HE

相对论恒星潮汐破裂事件中碎片的质量回落率

The mass fallback rate of the debris in relativistic stellar tidal disruption events

Taj Jankovič, Andreja Gomboc

备注：: 18 pages, 11 figures, accepted for publication in ApJ
DOI：: 10.3847/1538-4357/acb8b0

摘要：

高能恒星潮汐破裂事件（TDEs）提供了一种研究黑洞特征及其环境的方法。我们模拟TDE与PHANTOM代码在广义相对论和牛顿描述的超大质量黑洞的引力。用恒星演化程序MESA构造了不同参数$β$的抛物轨道上的恒星，从而得到了真实的恒星密度分布。研究了碎片$\dot{M}$的质量回落率及其与$β$、恒星质量和年龄、黑洞自旋以及引力描述的选择的关系。我们计算峰值$\dot{M}_\mathrm{peak}$、达到峰值$t_\mathrm{peak}$的时间、超爱丁顿相$t_\mathrm{Edd}$的持续时间、$\dot{M}>0.5\dot{M}_\mathrm{peak}$的时间$t_{>0.5\dot{M}_\mathrm{peak}}$、早期上升时间$τ_\mathrm{rise}$和晚期斜率$n_\infty$。我们用$β$、恒星质量和年龄恢复了$\dot{M}_\mathrm{peak}$、$t_\mathrm{peak}$、$τ_\mathrm{rise}$和$n_\infty$的变化趋势。我们发现，$t_\mathrm{Edd}$，在一个固定的$β$，标度主要与恒星的质量，而$t_{>0.5\dot{M}_\mathrm{peak}}$标度与恒星的紧凑性。SMBH自转的影响取决于其自转轴相对于初始轨道上恒星运动方向的取向。在逆行轨道上相遇导致$\dot{M}$曲线变窄，$\dot{M}_\mathrm{peak}$变高，而逆行轨道则相反。我们发现，中断，在相同的近心距离，在相对论潮汐场比在牛顿更强。因此，相对论性$\dot{M}$曲线具有较高的$\dot{M}_\mathrm{peak}$，以及较短的$t_\mathrm{peak}$和$t_\mathrm{Edd}$。

英文摘要：

Highly energetic stellar tidal disruption events (TDEs) provide a way to study black hole characteristics and their environment. We simulate TDEs with the PHANTOM code in a general relativistic and Newtonian description of a supermassive black hole's gravity. Stars, which are placed on parabolic orbits with different parameters $β$, are constructed with the stellar evolution code MESA and therefore have realistic stellar density profiles. We study the mass fallback rate of the debris $\dot{M}$ and its dependence on the $β$, stellar mass and age as well as the black hole's spin and the choice of the gravity's description. We calculate peak value $\dot{M}_\mathrm{peak}$, time to the peak $t_\mathrm{peak}$, duration of the super-Eddington phase $t_\mathrm{Edd}$, time $t_{>0.5\dot{M}_\mathrm{peak}}$ during which $\dot{M}>0.5\dot{M}_\mathrm{peak}$, early rise-time $τ_\mathrm{rise}$ and late-time slope $n_\infty$. We recover the trends of $\dot{M}_\mathrm{peak}$, $t_\mathrm{peak}$, $τ_\mathrm{rise}$ and $n_\infty$ with $β$, stellar mass and age, which were obtained in previous studies. We find that $t_\mathrm{Edd}$, at a fixed $β$, scales primarily with the stellar mass, while $t_{>0.5\dot{M}_\mathrm{peak}}$ scales with the compactness of stars. The effect of SMBH's rotation depends on the orientation of its rotational axis relative to the direction of the stellar motion on the initial orbit. Encounters on prograde orbits result in narrower $\dot{M}$ curves with higher $\dot{M}_\mathrm{peak}$, while the opposite occurs for retrograde orbits. We find that disruptions, at the same pericenter distance, are stronger in a relativistic tidal field than in a Newtonian. Therefore, relativistic $\dot{M}$ curves have higher $\dot{M}_\mathrm{peak}$, and shorter $t_\mathrm{peak}$ and $t_\mathrm{Edd}$.

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英文摘要：

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