Query : 2001A&A...379.1138M

2001A&A...379.1138M - Astronomy and Astrophysics, volume 379, 1138-1152 (2001/12-1)

Formation of a proto-quasar from accretion flows in a halo.


Abstract (from CDS):

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 and parameterized in terms of the spin parameter, λv, the redshift of collapse, zc, the fraction of baryons in stars, f*, and the efficiency of supernovae, ν. 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 10-100µG. In a model of a self-similar accretion flow in an initially dominant halo, it is shown that for typical halo parameters, about 108M accretes via small magnetic stresses (or alternatively by self-gravity induced instability or by alpha viscosity) in 108 years into a compact region. A model of a self-gravitating evolution of a compact magnetized disk (r0≲100pc), 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 a self-gravitating disk, obtained here, have general utility and can be adapted to other contexts like protostellar disks as well. Implications of this work for dwarf galaxy formation, and a residual large scale seed field, are also breifly discussed.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - magnetic fields - galaxies: formation - cosmology: theory

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 M 106 Sy2 12 18 57.620 +47 18 13.39   9.14 8.41 8.11   ~ 2317 3
2 M 87 AGN 12 30 49.42338414 +12 23 28.0436859 10.16 9.59 8.63   7.49 ~ 7020 3

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