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Consistent Analysis of the AGN LF in X-Ray and MIR in the XMM-LSS Field

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jats:titleAbstract</jats:title> jats:pThe luminosity function of active galactic nuclei (AGN) probes the history of supermassive black hole assembly and growth across cosmic time. To mitigate selection biases, we present a consistent analysis of the AGN luminosity functions (LFs) derived for both X-ray and mid-infrared (MIR) selected AGN in the XMM-Large Scale Structure field. There are 4268 AGN used to construct the MIR luminosity function (IRLF) and 3427 AGN used to construct the X-ray luminosity function (XLF), providing the largest census of the AGN population out to jats:italicz</jats:italic> = 4 in both bands with significant reduction in uncertainties. We are able for the first time to see the knee of the IRLF at jats:italicz</jats:italic> > 2 and observe a flattening of the faint-end slope as redshift increases. The bolometric luminosity density, a proxy for the cosmic black hole accretion history, computed from our LFs, shows a peak at jats:italicz</jats:italic> ≈ 2.25, consistent with recent estimates of the peak in the star formation rate density (SFRD). However, at earlier epochs, the AGN luminosity density is flatter than the SFRD. If confirmed, this result suggests that the build up of black hole mass outpaces the growth of stellar mass in high-mass systems at jats:italicz</jats:italic> ≳ 2.5. This is consistent with observations of redshift jats:italicz</jats:italic> ∼ 6 quasars that lie above the local jats:italicM</jats:italic> − jats:italicσ</jats:italic> relationship. The luminosity density derived from the IRLF is higher than that from the XLF at all redshifts. This is consistent with the dominant role of obscured AGN activity in the cosmic growth of supermassive black holes.</jats:p>



5101 Astronomical Sciences, 51 Physical Sciences

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Astrophysical Journal

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American Astronomical Society
NSF (AST-1934744)