2014/12/31 by Hikari Shirakata, Takashi Okamoto, Motohiro Enoki +4
Physics and Astronomy · #Accretion (finance) #Active galactic nucleus #Astronomy #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics #Attenuation #Black hole (networking) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminosity #Physics #Quasar #astro-ph.GA
paper · pdf · doi:10.1093/mnrasl/slv035
5 pages, 4 figures, 1 tables. Accepted for publication by MNRAS Letters
arxiv created 2015/02/24 · openalex publication_date 2015/03/27 · arxiv updated 2015/05/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract We have investigated effects of dust attenuation on quasar luminosity functions at z ∼ 2 using a semi-analytic galaxy formation model combined with a large cosmological N-body simulation. We estimate the dust attenuation of quasars self-consistently with that of galaxies by considering the dust in their host bulges. We find that the luminosity of the bright quasars is strongly dimmed by the dust attenuation, ∼2 mag in the B-band. Assuming the empirical bolometric corrections for active galactic nuclei (AGNs) by Marconi et al., we find that this dust attenuation is too strong to explain the B-band and X-ray quasar luminosity functions simultaneously. We consider two possible mechanisms that weaken the dust attenuation. As such a mechanism, we introduce a time delay for AGN activity, that is, gas fuelling to a central black hole starts sometime after the beginning of the starburst induced by a major merger. The other is the anisotropy in the dust distribution. We find that in order to make the dust attenuation of the quasars negligible, either the gas accretion into the black holes has to be delayed at least three times the dynamical time-scale of their host bulges or the dust covering factor is as small as ∼0.1.