%0 Generic %1 zhang2020effects %A Zhang, Xiaoxia %A Lu, Youjun %A Fang, Taotao %D 2020 %K library %T Effects of spin on constraining the seeds and growth of $\gtrsim 10^9M_ødot$ supermassive black holes in $z>6.5$ Quasars %U http://arxiv.org/abs/2010.06128 %X The existence of $\gtrsim10^9M_ødot$ supermassive black holes (SMBHs) at redshift $z>6$ raises the problem of how such SMBHs can grow up within the cosmic time ($<1$\,Gyr) from small seed BHs. In this letter, we use the observations of $14$ Quasars at $z>6.5$ with mass estimates to constrain their seeds and early growth, by self-consistently considering the spin evolution and the possibility of super-Eddington accretion. We find that spin plays an important role in the growth of early SMBHs, and the constraints on seed mass and super-Eddington accretion fraction strongly depend on the assumed accretion history. If the accretion is coherent with single (or a small number of) episode(s), leading to high spins for the majority of accretion time, then the SMBH growth is relatively slow; and if the accretion is chaotic with many episodes and in each episode the total accreted mass is much less than the SMBH mass, leading to moderate/low spins, then the growth is relatively fast. The constraints on the seed mass and super-Eddington accretion fraction are degenerate. A significant fraction ($\gtrsim0.1\%-1\%$ in linear scale but $3-4$ dex in logarithmic scale for $10^3-10^4 M_ødot$ seeds) of super-Eddington accretion is required if the seed mass is not $\gg10^5M_ødot$, and the requirements of high seed-mass and/or super-Eddington accretion fraction are moderately relaxed if the accretion is chaotic.

@misc{zhang2020effects, abstract = {The existence of $\gtrsim10^9M_\odot$ supermassive black holes (SMBHs) at redshift $z>6$ raises the problem of how such SMBHs can grow up within the cosmic time ($<1$\,Gyr) from small seed BHs. In this letter, we use the observations of $14$ Quasars at $z>6.5$ with mass estimates to constrain their seeds and early growth, by self-consistently considering the spin evolution and the possibility of super-Eddington accretion. We find that spin plays an important role in the growth of early SMBHs, and the constraints on seed mass and super-Eddington accretion fraction strongly depend on the assumed accretion history. If the accretion is coherent with single (or a small number of) episode(s), leading to high spins for the majority of accretion time, then the SMBH growth is relatively slow; and if the accretion is chaotic with many episodes and in each episode the total accreted mass is much less than the SMBH mass, leading to moderate/low spins, then the growth is relatively fast. The constraints on the seed mass and super-Eddington accretion fraction are degenerate. A significant fraction ($\gtrsim0.1\%-1\%$ in linear scale but $\sim 3-4$ dex in logarithmic scale for $10^3-10^4 M_\odot$ seeds) of super-Eddington accretion is required if the seed mass is not $\gg10^{5}M_\odot$, and the requirements of high seed-mass and/or super-Eddington accretion fraction are moderately relaxed if the accretion is chaotic.}, added-at = {2020-10-14T08:11:59.000+0200}, author = {Zhang, Xiaoxia and Lu, Youjun and Fang, Taotao}, biburl = {https://www.bibsonomy.org/bibtex/2b2b41a801ce6bc96fbf8777de6a6c3a5/gpkulkarni}, description = {Effects of spin on constraining the seeds and growth of $\gtrsim 10^9M_\odot$ supermassive black holes in $z>6.5$ Quasars}, interhash = {7674d386a9eee4a0ea9155036ca14c89}, intrahash = {b2b41a801ce6bc96fbf8777de6a6c3a5}, keywords = {library}, note = {cite arxiv:2010.06128Comment: 7 pages, 2 figures, 1 table. Accepted for publication in ApJL}, timestamp = {2020-10-14T08:11:59.000+0200}, title = {Effects of spin on constraining the seeds and growth of $\gtrsim 10^9M_\odot$ supermassive black holes in $z>6.5$ Quasars}, url = {http://arxiv.org/abs/2010.06128}, year = 2020 }