http://arxiv.org/abs/1602.04293
We analyze the early growth stage of direct-collapse black holes (DCBHs) with $\sim 10^{5} \ \rm M_\odot$, which are formed by collapse of supermassive stars in atomic-cooling halos at $z \gtrsim 10$. A nuclear accretion disk around a newborn DCBH is gravitationally unstable and fragments into clumps with a few $10 \ \rm M_\odot$ at $\sim 0.01-0.1 \ \rm pc$ from the center. Such clumps evolve into massive metal-poor stars with a few $10-100 \ \rm M_\odot$ via successive gas accretion and a nuclear star cluster is formed. Radiative and mechanical feedback from an inner slim disk and the star cluster will significantly reduce the gas accretion rate onto the DCBH within $\sim 10^6$ yr. Some of the nuclear stars can be scattered onto the loss cone orbits also within $\lesssim 10^6$ yr and tidally disrupted by the central DCBH. The jet luminosity powered by such tidal disruption events can be $L_{\rm j} \gtrsim 10^{50} \ \rm erg \ s^{-1}$. The prompt emission will be observed in X-ray bands with a peak duration of $\delta t_{\rm obs} \sim 10^{5-6} \ (1+z) \ \rm s$ followed by a tail $\propto t_{\rm obs}^{-5/3}$, which can be detectable by {\it Swift} BAT and eROSITA even from $z \sim 20$. Follow-up observations of the radio afterglows with, e.g., VLA and the host halos with JWST can probe the earliest AGN feedback from DCBHs.
K. Kashiyama and K. Inayoshi
Tue, 16 Feb 16
27/71
Comments: 8 pages, 1 figure, submitted to ApJ, comments are welcome
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