Effects of Spin on Constraining the Seeds and Growth of ?109M⊙ Supermassive Black Holes in z > 6.5 Quasars
Zhang,Xiaoxia1; Lu,Youjun2,3; Fang,Taotao1
Source PublicationThe Astrophysical Journal Letters
AbstractAbstract The existence of ?109M⊙ 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 (?0.1%–1% in linear scale but ~3–4 dex in logarithmic scale for 103–104M⊙ seeds) of super-Eddington accretion is required if the seed mass is not ?105M⊙, and the requirements of high seed mass and/or super-Eddington accretion fraction are moderately relaxed if the accretion is chaotic.
KeywordAccretion Black hole physics Early universe Galaxy nuclei Quasars Supermassive black holes
WOS IDIOP:2041-8205-903-1-abc077
PublisherThe American Astronomical Society
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Document Type期刊论文
Corresponding AuthorZhang,Xiaoxia
Affiliation1.Department of Astronomy, Xiamen University, Xiamen, Fujian 361005, People's Republic of China;,
2.National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing 100101, People's Republic of China;
3.School of Astronomy and Space Sciences, University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, People's Republic of China
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GB/T 7714
Zhang,Xiaoxia,Lu,Youjun,Fang,Taotao. Effects of Spin on Constraining the Seeds and Growth of ?109M⊙ Supermassive Black Holes in z > 6.5 Quasars[J]. The Astrophysical Journal Letters,2020,903(1).
APA Zhang,Xiaoxia,Lu,Youjun,&Fang,Taotao.(2020).Effects of Spin on Constraining the Seeds and Growth of ?109M⊙ Supermassive Black Holes in z > 6.5 Quasars.The Astrophysical Journal Letters,903(1).
MLA Zhang,Xiaoxia,et al."Effects of Spin on Constraining the Seeds and Growth of ?109M⊙ Supermassive Black Holes in z > 6.5 Quasars".The Astrophysical Journal Letters 903.1(2020).
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