PRIMUS: An Observationally Motivated Model to Connect the Evolution of the Active Galactic Nucleus and Galaxy Populations out to z ~ 1
Aird, James ( Department of Physics, Durham University, Durham DH1 3LE, UK ; COFUND Junior Research Fellow.; ); Coil, Alison L. ( Center for Astrophysics and Space Sciences, Department of Physics, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093, USA ; Alfred P. Sloan Foundation Fellow. ); Moustakas, John ( Department of Physics and Astronomy, Siena College, 515 Loudon Road, Loudonville, NY 12211, USA ); Diamond-Stanic, Aleksandar M. ( Center for Astrophysics and Space Sciences, Department of Physics, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093, USA ; Center for Galaxy Evolution Fellow. ); Blanton, Michael R. ( Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA ); Cool, Richard J. ( MMT Observatory, 1540 E Second Street, University of Arizona, Tucson, AZ 85721, USA ); Eisenstein, Daniel J. ( Harvard College Observatory, 60 Garden Street, Cambridge, MA 02138, USA ); Wong, Kenneth C. ( Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA ); Zhu, Guangtun ( Department of Physics & Astronomy, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA ) show affiliations
The Astrophysical Journal, Volume 775, Issue 1, article id. 41, 12 pp. (2013).
Published in Sep 2013
We present an observationally motivated model to connect the active galactic nucleus (AGN) and galaxy populations at 0.2 〈 z 〈 1.0 and predict the AGN X-ray luminosity function (XLF). We start with measurements of the stellar mass function of galaxies (from the Prism Multi-object Survey) and populate galaxies with AGNs using models for the probability of a galaxy hosting an AGN as a function of specific accretion rate. Our model is based on measurements indicating that the specific accretion rate distribution is a universal function across a wide range of host stellar masses with slope γ1 ≈ -0.65 and an overall normalization that evolves with redshift. We test several simple assumptions to extend this model to high specific accretion rates (beyond the measurements) and compare the predictions for the XLF with the observed data. We find good agreement with a model that allows for a break in the specific accretion rate distribution at a point corresponding to the Eddington limit, a steep power-law tail to super-Eddington ratios with slope \gamma _2=-2.1^{+0.3}_{-0.5}, and a scatter of 0.38 dex in the scaling between black hole and host stellar mass. Our results show that samples of low luminosity AGNs are dominated by moderately massive galaxies ( {M_*}\sim 10^{10}{--}10^{11} {M}_\odot) growing with a wide range of accretion rates due to the shape of the galaxy stellar mass function rather than a preference for AGN activity at a particular stellar mass. Luminous AGNs may be a severely skewed population with elevated black hole masses relative to their host galaxies and in rare phases of rapid accretion.
Astronomy: X-rays: galaxies; galaxies: active; galaxies: evolution
arXiv: Astrophysics - Cosmology and Extragalactic Astrophysics