Cosmological evolution of massive black holes: effects of Eddington ratio distribution and quasar lifetime - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




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Abstract: A power-law time-dependent lightcurve for active galactic nuclei AGNs isexpected by the self-regulated black hole growth scenario, in which thefeedback of AGNs expels gas and shut down accretion. This is also supported bythe observed power-law Eddington ratio distribution of AGNs. At high redshifts,the AGN life timescale is comparable with or even shorter than the age of theuniverse, which set a constraint on the minimal Eddington ratio for AGNs on theassumption of a power-law AGN lightcurve. The black hole mass function BHMFof AGN relics is calculated by integrating the continuity equation of massiveblack hole number density on the assumption of the growth of massive blackholes being dominated by mass accretion with a power-law Eddington ratiodistribution for AGNs. The derived BHMF of AGN relics at z=0 can fit themeasured local mass function of the massive black holes in galaxies quite well,provided the radiative efficiency ~0.1 and a suitable power-law index for theEddington ratio distribution are adopted. In our calculations of the black holeevolution, the duty cycle of AGN should be less than unity, which requires thequasar life timescale >0.5 giga-years.



Autor: Xinwu Cao Shanghai Astronomical Observatory

Fuente: https://arxiv.org/







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