GROWTH OF MASSIVE BLACK HOLES AT THEIR LATE STAGE

Journal Article · Sun Jun 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/716/2/1423· OSTI ID:21452911

Yadi, Xu ^[1]

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1. Physics Department, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

It is believed that the growth of local massive black holes was dominated by accretion during quasar phases, while a fraction of the local black hole mass was accumulated through accreting gases at very low rates. We derive the black hole mass density as a function of redshift with the bolometric luminosity function of active galactic nuclei (AGNs) assuming that massive black holes grew via accreting the circumnuclear gases, in which the derived black hole mass density is required to match the measured local black hole mass density at z = 0. Advection-dominated accretion flows (ADAFs) are supposed to be present in low-luminosity AGNs/normal galaxies, which are very hot and radiate mostly in the hard X-ray band. Most of the X-ray background (XRB) is contributed by bright AGNs, and a variety of AGN population synthesis models were developed to model the observed XRB in the last two decades. Based on our derived black hole mass density, we calculate the contribution to the XRB from the ADAFs in faint AGNs/normal galaxies with a given Eddington ratio distribution, which is mostly in the hard X-ray energy band with an energy peak at {approx}200 keV. The growth of massive black holes during the ADAF phase can therefore be constrained with the observed XRB. Combining an AGN population synthesis model with our results, we find that the fitting on the observed XRB, especially at the hard X-ray energy band with {approx_gt}100 keV, is improved provided the contribution of the ADAFs in low-luminosity AGNs/normal galaxies is properly included. It is found that less than {approx}15% of local massive black hole mass density was accreted during ADAF phases. We suggest that more accurate measurements of the XRB in the energy band with {approx_gt}100 keV in the future may help constrain the growth of massive black holes at their late stage. We also calculate their contribution to the extragalactic {gamma}-ray background (EGRB), and find that less than {approx}1% of the observed EGRB is contributed by the ADAFs in these faint sources.

• OSTI ID: 21452911
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 716; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
ADVECTION
BLACK HOLES
BOLOMETERS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
GALAXIES
GALAXY NUCLEI
GAMMA RADIATION
HARD X RADIATION
IONIZING RADIATIONS
LUMINOSITY
MASS TRANSFER
MEASURING INSTRUMENTS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
QUASARS
RADIATIONS
RED SHIFT
X RADIATION