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arXiv 2310.07090astro-ph.HE
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低质量比超大质量黑洞双星中激波驱动的周期性变化

Shock-Driven Periodic Variability in a Low-Mass-Ratio Supermassive Black Hole Binary

K. Whitley, A. Kuznetsova, K. Gültekin, M. Ruszkowski

AI总结:

通过2D水动力学模拟低质量比SMBHB,发现其偏心间隙驱动与轨道周期匹配的周期性吸积和激波,激波光度峰值滞后吸积率峰值0.43个周期,提出利用X射线和紫外相关变化性作为SMBHB候选体的有效标识。

摘要:

我们研究了嵌入环主星盘的低质量比超大质量黑洞双星(SMBHB)随时间变化的电磁辐射,特别关注由双星驱动的激波变化性。我们使用物理上自洽的稳态盘模型,对质量比 $q=0.01$、间距 $a=100\\;R_g$ 的 SMBHB 进行了 2D 局部等温水动力学模拟。我们通过监测次级黑洞上的吸积并使用人工粘性方案来捕捉激波和监测能量耗散,从而估计该系统的电磁变化性。该 SMBHB 在盘中产生了一个宽阔的偏心间隙,这以前只在较大质量比下观察到,我们将其归因于我们的盘模型比以前的工作薄得多(在次级黑洞附近 $H/R\approx0.01$)。该偏心间隙在与双星轨道周期匹配的时间尺度上驱动次级 SMBH 的周期性吸积,$t_{\rm{bin}}\approx0.1\\;\rm{yr}$,这意味着 SMBHB 参数空间的可变吸积区延伸到了比以前确定的更低的质量比。双星驱动的激波是周期性的,周期与轨道周期匹配,并且激波与吸积率相关,激波光度的峰值滞后吸积率峰值 $0.43\\;t_{\rm{bin}}$。我们提出,这些量的相关性代表了 SMBHB 候选者的有用标识,即通过对 AGN 的 X 射线和紫外监测观察相关变化性,而不是仅依靠单波段周期性。

英文摘要:

We investigate the time-varying electromagnetic emission of a low-mass-ratio supermassive black hole binary (SMBHB) embedded in a circumprimary disk, with a particular interest in variability of shocks driven by the binary. We perform a 2D, locally isothermal hydrodynamics simulation of a SMBHB with mass ratio $q=0.01$ and separation $a=100\;R_g$, using a physically self-consistent steady disk model. We estimate the electromagnetic variability from the system by monitoring accretion onto the secondary and using an artificial viscosity scheme to capture shocks and monitor the energy dissipated. The SMBHB produces a wide, eccentric gap in the disk, previously only observed for larger mass ratios, which we attribute to our disk model being much thinner ($H/R\approx0.01$ near the secondary) than is typical of previous works. The eccentric gap drives periodic accretion onto the secondary SMBH on a timescale matching the orbital period of the binary, $t_{\rm{bin}}\approx0.1\;\rm{yr}$, implying that the variable accretion regime of the SMBHB parameter space extends to lower mass ratios than previously established. Shocks driven by the binary are periodic, with a period matching the orbital period, and the shocks are correlated with the accretion rate, with peaks in the shock luminosity lagging peaks in the accretion rate by $0.43\;t_{\rm{bin}}$. We propose that the correlation of these quantities represents a useful identifier of SMBHB candidates, via observations of correlated variability in X-ray and UV monitoring of AGN, rather than single-waveband periodicity alone.

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