Growth of massive black holes during radiatively inefficient accretion phases

	Growth of massive black holes during radiatively inefficient accretion phases
	Cao, Xinwu
刊名	ASTROPHYSICAL JOURNAL
	2007-04-20
卷号	659 期号:2 页码:950-957
关键词	accretion black hole physics galaxies : active quasars : general X-rays : diffuse background accretion disks
英文摘要	We derive the black hole mass density as a function of redshift from the hard X-ray active galactic nucleus (AGN) luminosity function, assuming that massive black holes grow via accreting circumnuclear gases. The derived black hole mass density matches the measured local black hole mass density at z = 0, which requires the average radiative efficiency of AGNs to be similar to 0.1-0.17. The massive black holes in most faint AGNs and even normal galaxies are still accreting gases, although their accretion rates are very low. Radiatively inefficient accretion flows (RIAFs) are supposed in these faint sources, which should radiate mostly in the hard X-ray band. We calculate the contribution to the X-ray background (XRB) from both the bright AGNs and the RIAFs in faint AGNs and normal galaxies. Our calculations show that both the observed intensity and spectral shape of the XRB with an energy peak at similar to 30 keV can be well reproduced without including the emission of Compton-thick AGNs, if the massive black holes in faint AGNs and normal galaxies are spinning rapidly, with a similar to 0.9, and are accreting at rates of m similar to (1.0-3.0); 10(-4). It indicates that less than similar to 5% of the local massive black hole mass density was accreted during radiatively inefficient accretion phases, which is obviously only an upper limit, because Compton-thick AGNs have not been considered. If the same number of Compton-thick AGNs with log N(H) 24-25 as those with log N(H) 23-24 is considered, the fraction of the local black hole mass density accumulated during inefficient accretion phases should be lower than similar to 2%. The constraints of the XRB can provide upper limits on the average accretion rate for inactive galaxies.
学科主题	星系与宇宙学研究中心
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	ACTIVE GALACTIC NUCLEI ; ADVECTION-DOMINATED ACCRETION ; RAY LUMINOSITY FUNCTION ; COSMOLOGICAL EVOLUTION ; GALAXIES ; QUASARS ; CONSTRAINTS ; ORIGIN ; FLOWS ; MODEL
收录类别	SCI
语种	英语
WOS记录号	WOS:000245774700008
公开日期	2010-11-08
内容类型	期刊论文
源URL	[http://119.78.226.72//handle/331011/12453]
专题	上海天文台_星系宇宙学重点实验室
作者单位	Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China
推荐引用方式 GB/T 7714	Cao, Xinwu. Growth of massive black holes during radiatively inefficient accretion phases[J]. ASTROPHYSICAL JOURNAL,2007,659(2):950-957.
APA	Cao, Xinwu.(2007).Growth of massive black holes during radiatively inefficient accretion phases.ASTROPHYSICAL JOURNAL,659(2),950-957.
MLA	Cao, Xinwu."Growth of massive black holes during radiatively inefficient accretion phases".ASTROPHYSICAL JOURNAL 659.2(2007):950-957.