Revisiting Soltan’s argument based on a semi-analytical model for galaxy and black hole evolution. (arXiv:2006.02436v1 [astro-ph.GA])

Revisiting Soltan’s argument based on a semi-analytical model for galaxy and black hole evolution. (arXiv:2006.02436v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Shirakata_H/0/1/0/all/0/1">Hikari Shirakata</a> (1,2), <a href="http://arxiv.org/find/astro-ph/1/au:+Kawaguchi_T/0/1/0/all/0/1">Toshihiro Kawaguchi</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Okamoto_T/0/1/0/all/0/1">Takashi Okamoto</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Nagashima_M/0/1/0/all/0/1">Masahiro Nagashima</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Oogi_T/0/1/0/all/0/1">Taira Oogi</a> (5) ((1) Hokkaido University, (2) Tadano Ltd. (3) Onomichi City University, (4) Bunkyo University, (5) KAVLI IPMU, The University of Tokyo)

We show the significance of the super-Eddington accretion for the cosmic
growth of supermassive black holes (SMBHs) with a semi-analytical model for
galaxy and black hole evolution. The model explains various observed properties
of galaxies and active galactic nuclei at a wide redshift range. By tracing the
growth history of individual SMBHs, we find that the fraction of the SMBH mass
acquired during the super-Eddington accretion phases to the total SMBH mass
becomes larger for less massive black holes and at higher redshift. Even at z =
0, SMBHs with > 1e+9 Msun have acquired more than 50% of their mass by
super-Eddington accretions, which is apparently inconsistent with classical
Soltan’s argument. However, the mass-weighted radiation efficiency of SMBHs
with > 1e+8 Msun obtained with our model, is about 0.08 at z = 0, which is
consistent with Soltan’s argument within the observational uncertainties. We,
therefore, conclude that Soltan’s argument cannot reject the possibility that
SMBHs are grown mainly by super-Eddington accretions.

We show the significance of the super-Eddington accretion for the cosmic
growth of supermassive black holes (SMBHs) with a semi-analytical model for
galaxy and black hole evolution. The model explains various observed properties
of galaxies and active galactic nuclei at a wide redshift range. By tracing the
growth history of individual SMBHs, we find that the fraction of the SMBH mass
acquired during the super-Eddington accretion phases to the total SMBH mass
becomes larger for less massive black holes and at higher redshift. Even at z =
0, SMBHs with > 1e+9 Msun have acquired more than 50% of their mass by
super-Eddington accretions, which is apparently inconsistent with classical
Soltan’s argument. However, the mass-weighted radiation efficiency of SMBHs
with > 1e+8 Msun obtained with our model, is about 0.08 at z = 0, which is
consistent with Soltan’s argument within the observational uncertainties. We,
therefore, conclude that Soltan’s argument cannot reject the possibility that
SMBHs are grown mainly by super-Eddington accretions.

http://arxiv.org/icons/sfx.gif

Comments are closed.