Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-10-28
Astron.Astrophys. 379 (2001) 1138
Astronomy and Astrophysics
Astrophysics
15 pages, 6 Figures, In Press in Astronomy & Astrophysics
Scientific paper
10.1051/0004-6361:20011405
We present a detailed model for the formation of massive objects at the centers of galaxies. The effects of supernovae heating and the conditions of gas loss are revisited. The escape time of the gas is compared with the cooling time, which provides an additional condition not previously considered. Its consequences for the allowed mass range of the halo is calculated. It is shown that sufficient gas is retained to form massive dark objects and quasars even for moderately massive halos but a decline is expected at low redshifts. Subsequently, a gaseous disk forms with a radial extent of a ~kpc, spun up by tidal torques and magnetized by supernovae fields with fields strengths of $10-100 \mu G$. In a model of a self-similar accretion flow in an initially dominant halo, it is shown that for typical halo parameters, about $10^8 M_\odot$ accretes via small magnetic stresses (or alternatively by self-gravity induced instability or by alpha viscosity) in $10^8$ years into a compact region. A model of a self-gravitating evolution of a compact magnetized disk, which is relevant when a significant fraction of the disk mass falls in, is presented, and it has a rapid collapse time scale of a million years. The two disk solutions, one for accretion in an imposed halo potential and the other for self-gravitating disk, obtained here, have general utility and can be adapted to other contexts like protostellar disks as well.
No associations
LandOfFree
Formation of a Proto-Quasar from Accretion Flows in a Halo 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 Formation of a Proto-Quasar from Accretion Flows in a Halo, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Formation of a Proto-Quasar from Accretion Flows in a Halo will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-270556