Primus: The Dependence of Agn Accretion on Host Stellar Mass and Color

Abstract

We present evidence that the incidence of active galactic nuclei (AGNs) and the distribution of their accretion rates do not depend on the stellar masses of their host galaxies, contrary to previous studies. We use hard (2−10 keV) X-ray data from three extragalactic fields (XMM-LSS, COSMOS and ELAIS-S1) with redshifts from the Prism Multi-object Survey to identify 242 AGNs with L 2−10 keV = 10 42−44 erg s −1 within a parent sample of ∼25,000 galaxies at 0.2 < z < 1.0 over ∼ 3.4 deg 2 and to i ∼ 23. We find that although the fraction of galaxies hosting an AGN at fixed X-ray luminosity rises strongly with stellar mass, the distribution of X-ray luminosities is independent of mass. Furthermore, we show that the probability that a galaxy will host an AGN can be defined by a universal Eddington ratio distribution that is independent of the host galaxy stellar mass and has a power-law shape with slope −0.65. These results demonstrate that AGNs are prevalent at all stellar masses in the range 9.5 < log M * /M ⊙ < 12 and that the same physical processes regulate AGN activity in all galaxies in this stellar mass range. While a higher AGN fraction may be observed in massive galaxies, this is a selection effect related to the underlying Eddington ratio distribution. We also find that the AGN fraction drops rapidly between z ∼ 1 and the present day and is moderately enhanced (factor∼ 2) in galaxies with blue or green optical colors. Consequently, while AGN activity and star formation appear to be globally correlated, we do not find evidence that the presence of an AGN is related to the quenching of star formation or the color transformation of galaxies.

Clustering of intermediate redshift quasars using the final SDSS III-BOSS sample

“…We conclude that there must be substantial scatter between halo mass and quasar luminosity in this redshift/luminosity range. A broad short-timescale scatter in Eddington ratio has been proposed both from observational and theoretical standpoints in previous studies (e.g., Hopkins & Hernquist 2009;Kauffmann & Heckman 2009;Novak, Ostriker & Ciotti 2011;Aird et al 2012;Bongiorno et al 2012;Gabor & Bournaud 2013;Hickox et al 2014;Veale, White & Conroy 2014;Schawinski et al 2015), which further argues against a tight, monotonic relationship between luminosity and mass. Our conclusion is stronger than that reached from previous studies at lower redshift because of our high statistical precision and because the high bias of our quasars puts us on the steeply rising portion of the…”

The cosmic growth of the active black hole population at 1 <z <2 in zCOSMOS, VVDS and SDSS

“…In general, AGN show a broad range of levels of activity (e.g. Heckman et al 2004;Hickox et al 2009;Aird et al 2012;Bongiorno et al 2012), down to accretion rates well below 0.01(e.g. Soria et al 2006;Ho 2008;Gallo et al 2010;Miller et al 2012).…”

“…Aird et al (2012) determined the specific accretion rate distribution function of type-2 AGN at 0.2 < z < 1.0, defined as the distribution function of the ratio of AGN luminosity over stellar mass. This quantity is effectively the convolution of the ERDF with the M• − M Bulge relation.…”

The dark matter haloes of moderate luminosity X-ray AGN as determined from weak gravitational lensing and host stellar masses

“…Heckman et al 2004;Kauffmann & Heckman 2009;Schulze & Wisotzki 2010;Aird et al 2012). For a fixed L X cut, we sample AGN in massive galaxies over a wide range of Eddington ratios, while for less massive galaxies we only sample AGN with larger Eddington ratios (Schulze & Wisotzki 2010;Aird et al 2012). This may lead to an apparent increase in f A with halo mass for L X -selected samples.…”