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arXiv 1903.09124astro-ph.GAastro-ph.HE
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星系合并残余物中潮汐破坏事件的发生率

Tidal disruption event rates in galaxy merger remnants

Hugo Pfister, Ben Bar-Or, Marta Volonteri, Yohan Dubois, Pedro R. Capelo

摘要:

潮汐破裂事件(TDEs)的速率敏感地依赖于银河系中央区域的恒星性质。模拟显示,星系合并会导致气体流入,引发核恒星爆发,增加中心恒星密度。出于这些数值结果,并通过观察到的过度代表性的后星暴星系之间的TDE主机,我们研究的TDE率的演变在高分辨率的流体动力学模拟的星系合并,在其中我们捕获的恒星密度的演变周围的大质量黑洞(BH)。我们应用损失锥理论的分析估计,使用模拟的恒星密度分布,估计TDE率的时间演化。在第二近心点,一个核星爆提高了黑洞周围的恒星密度在质量最小的星系,导致增强的TDE率周围的次级黑洞,虽然幅度和持续时间的增加取决于恒星形成的随机性非常小的尺度。主黑洞周围的中心恒星密度保持相当恒定,其TDE率也是如此。双星形成后,恒星密度降低,TDE率也降低。

英文摘要:

The rate of tidal disruption events (TDEs) depends sensitively on the stellar properties of the central galactic regions. Simulations show that galaxy mergers cause gas inflows, triggering nuclear starbursts, increasing the central stellar density. Motivated by these numerical results, and by the observed over-representation of post-starburst galaxies among TDE hosts, we study the evolution of the TDE rate in high-resolution hydrodynamical simulations of a galaxy merger, in which we capture the evolution of the stellar density around the massive black holes (BHs). We apply analytical estimates of the loss-cone theory, using the stellar density profiles from simulations, to estimate the time evolution of the TDE rate. At the second pericentre, a nuclear starburst enhances the stellar density around the BH in the least massive galaxy, leading to an enhancement of the TDE rate around the secondary BH, although the magnitude and the duration of the increase depend on the stochasticity of star formation on very small scales. The central stellar density around the primary BH remains instead fairly constant, and so is its TDE rate. After the formation of the binary, the stellar density decreases, and so does the TDE rate.

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