Bolometric luminosity black hole growth time and slim accretion discs in active galactic nuclei

Research output: Contribution to journalArticlepeer-review

Abstract

We investigate the accretion rate, bolometric luminosity, black hole (BH) growth time and BH spin in a large active galactic nucleus (AGN) sample under the assumption that all such objects are powered via thin or slim accretion discs (ADs). We use direct estimates of the mass accretion rate, Ṁ, to show that many currently used values of Lbol and L/LEdd are either underestimated or overestimated because they are based on bolometric correction factors that are adjusted to the properties of moderately accreting AGNs and do not take into account the correct combination of BH mass, spin and accretion rate. The consistent application of AD physics to our sample of Sloan Digital Sky Survey (SDSS) AGNs leads to the following findings. (1) Even the most conservative assumption about the radiative efficiency of fastaccreting BHs shows that many of these sources must contain slim ADs. We illustrate this by estimating the fraction of such objects at various redshifts. (2) Many previously estimated BH growth times are inconsistent with the AD theory. In particular, the growth times of the fastest accreting BHs were overestimated in the past by large factors with important consequences to AGN evolution. (3) Currently used bolometric correction factors for low accretion rate very massive SDSS BHs are inconsistent with the AD theory. Applying the AD set of assumptions to such objects, combined with standard photoionization calculations of broad emission lines, leads to the conclusion that many such objects must contain fast-spinning BHs.

Original languageEnglish
Article numberstt2238
Pages (from-to)672-679
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume438
Issue number1
DOIs
StatePublished - Feb 2014

Keywords

  • Accretion, accretion discs
  • Galaxies: active
  • Galaxies: nuclei
  • Quasars: general

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