THE RADIATIVE EFFICIENCY OF ACCRETION FLOWS IN INDIVIDUAL ACTIVE GALACTIC NUCLEI

By S. Davis, Ari Laor. 2010

211 citations recorded by the source corpus.

The radiative efficiency of active galactic nucleus (AGN) is commonly estimated based on the total mass accreted and the total AGN light emitted per unit volume in the universe integrated over time (the Soltan argument). In individual AGNs, thin accretion disk model spectral fits can be used to deduce the absolute accretion rate , if the black hole mass M is known. The radiative efficiency η is then set by the ratio of the bolometric luminosity Lbol to . We apply this method to determine η in a sample of 80 Palomar–Green quasars with well-determined Lbol, where is set by thin accretion disk model fits to the optical luminosity density, and the M determination based on the bulge stellar velocity dispersion (13 objects) or the broad line region. We derive a mean log η = −1.05 ± 0.52 consistent with the Soltan-argument-based estimates. We find a strong correlation of η with M, rising from η ∼ 0.03 at M = 107 M☉ and L/LEdd ∼ 1 to η ∼ 0.4 at M = 109 M☉ and L/LEdd ∼ 0.3. This trend is related to the overall uniformity of Lopt/Lbol in our sample, particularly the lack of the expected increase in Lopt/Lbol with increasing M (and decreasing L/LEdd), which is a generic property of thermal disk emission at fixed η. The significant uncertainty in the M determination is not large enough to remove the correlation. The rising η with M may imply a rise in the black hole spin with M, as proposed based on other indirect arguments.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/55e63ccd0d4a05acda525768cc9bf6c35d710e02

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

SEMI-ANALYTIC GALAXY EVOLUTION (SAGE): MODEL CALIBRATION AND BASIC RESULTS (2016, background): “Recent hydrodynamic works have started to use η = 0.2 instead (e.g. Hirschmann et al. 2014; Sijacki et al. 2015), motivated by observations of more-luminous AGN (Yu & Tremaine 2002; Davis & Laor 2011, anti-respectively). work by C06.”
The dust covering factor in active galactic nuclei (2016, unknown): “The SED of the accretion disk is described by the following composition of power laws, in agreement with theoretical predictions and observational evidences (e.g Hubeny et al. 2001; Davis & Laor 2011; Slone & Netzer 2012; Capellupo et al. 2015): λLλ ∝ λ1.”
Cosmological simulations of black hole growth: AGN luminosities and downsizing (2013, methodology): “This choice is motivated by observations of Davis & Laor (2011) who find higher r for higher BH masses and by our numerical resolution.”