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The Accretion History of AGN I: Supermassive Black Hole Population Synthesis Model

7 Pith papers cite this work. Polarity classification is still indexing.

7 Pith papers citing it
abstract

As matter accretes onto the central supermassive black holes in active galactic nuclei (AGN), X-rays are emitted. We present a population synthesis model that accounts for the summed X-ray emission from growing black holes; modulo the efficiency of converting mass to X-rays, this is effectively a record of the accreted mass. We need this population synthesis model to reproduce observed constraints from X-ray surveys: the X-ray number counts, the observed fraction of Compton-thick AGN [$\log$ (N$_{\rm H}$/cm$^{\rm -2}$) $>$ 24] and the spectrum of the cosmic X-ray background (CXB), after accounting for selection biases. Over the past decade, X-ray surveys by {\it XMM-Newton}, {\it Chandra}, \textit{NuSTAR} and \textit{Swift}-BAT have provided greatly improved observational constraints. We find that no existing X-ray luminosity function (XLF) consistently reproduces all these observations. We take the uncertainty in AGN spectra into account, and use a neural network to compute an XLF that fits all observed constraints, including observed Compton-thick number counts and fractions. This new population synthesis model suggests that, intrinsically, 50$\pm$9\% (56$\pm$7\%) of all AGN within z $\simeq$ 0.1 (1.0) are Compton-thick.

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representative citing papers

An intrinsic decline of accretion activity in GRS 1915+105

astro-ph.HE · 2026-07-07 · conditional · novelty 6.0

Deep X-ray, radio, and infrared non-detections of GRS 1915+105 imply an intrinsic decline in accretion activity rather than enhanced obscuration, likely driven by 2023-2024 outflows clearing the inner disc.

Unification models of Active Galactic Nuclei

astro-ph.GA · 2026-06-10 · conditional · novelty 2.0

A review of AGN unification concluding that whether a black-hole-powered nucleus appears obscured depends on inclination, Eddington ratio (radiative feedback), and host-galaxy merger/redshift evolution.

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