2008/03/31 by Alireza Rafiee, Patrick B. Hall
Physics and Astronomy · #Accretion (finance) #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Physics #Quantum mechanics #Quasar #Radiation pressure #Radiative transfer #Radio Astronomy Observations and Technology #Redshift #Supermassive black hole #astro-ph
paper · pdf · doi:10.1088/0004-637x/691/1/425
published as Astrophys.J.691:425-430,2009 · 14 pages, 3 figures, accepted by ApJ on Sep 2008
arxiv created 2008/09/30 · openalex publication_date 2009/01/14 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Wang et al. estimated an average radiative efficiency of 30%–35% for quasars at moderate redshift. We find that their method is not independent of quasar lifetimes and thus that quasars do not necessarily have such high efficiencies. Nonetheless, it is possible to derive interrelated constraints on quasar lifetimes, Eddington ratios, and radiative efficiencies of supermassive BH. We derive such constraints using a statistically complete sample of quasars with BH mass estimates from broad Mg ii , made both with and without the radiation pressure correction of Marconi et al. We conclude that for quasars with L / L Edd ≳ 0.02, lifetimes can range from 140 to 750 Myr for Schwarzschild BHs. Coupled with observed BH masses, quasar lifetimes of ⩽ 140 Myr would imply that radiatively inefficient accretion or BH mergers must be important in the accretion history of quasars. Given reasonable assumptions about the quasar population, if the average quasar lifetime is <1 Gyr, and if radiatively inefficient accretion is unimportant, then not many BHs with Eddington ratio <0.2 can be rapidly spinning.