Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-12-30
Astrophys.J.659:950-957,2007
Astronomy and Astrophysics
Astrophysics
Astrophys.J. 659 (2006) 950-957
Scientific paper
10.1086/512116
The massive black holes in most faint active galactic nuclei (AGNs) and even normal galaxies are still accreting gases, though 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 from both the bright AGNs and the RIAFs in faint AGNs/normal galaxies. Our calculations show that both the observed intensity and spectral shape of the XRB with an energy peak at ~30$ keV can be well reproduced without including the emission of Compton-thick AGNs, if the massive black holes in faint AGNs/normal galaxies are spinning rapidly with a~0.9 and accreting at rates ~1.0-3.0\times 10^{-4}. It indicates that less than ~5 per cent of 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 the Compton-thick AGNs with log N_H=24-25 as those with log N_H=23-24 is considered, the fraction of local black hole mass density accumulated during inefficient accretion phases should be lower than ~2 per cent.
No associations
LandOfFree
Growth of massive black holes during radiatively inefficient accretion phases does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Growth of massive black holes during radiatively inefficient accretion phases, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Growth of massive black holes during radiatively inefficient accretion phases will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-485581