Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007aas...211.4521r&link_type=abstract
American Astronomical Society, AAS Meeting #211, #45.21; Bulletin of the American Astronomical Society, Vol. 39, p.799
Astronomy and Astrophysics
Astronomy
Scientific paper
Wang et al. (2006) estimated a high average radiative efficiency of 30% to 35% for quasars (actively accreting black holes) at moderate redshift, strongly suggesting that all supermassive black holes are rotating very rapidly. Their method for determining radiative efficiencies has two advantages: it deals with changes in quantities rather than absolutes and it is independent of obscured sources. However, we have investigated the reliability of the assumptions made by Wang et al. and have found that their method is not independent of quasar lifetimes. Nonetheless, given constraints on quasar lifetimes, their method can be used to constrain quasar radiative efficiencies and black hole spins. Conversely, the range of radiative efficiencies possible for the full range of black hole spins can be used to constrain the average lifetimes of quasars (assuming that luminous quasars are not powered by radiatively inefficient accretion flows). We will present interrelated constraints on quasar lifetimes, Eddington ratios and radiative efficiencies (black hole spins) from a statistically complete sample of SDSS quasars with black hole mass estimates from Mg II.
PBH and AR are supported in part by NSERC.
Hall Patrick B.
Rafiee Alireza
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