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Arxiv: Reconstruction of Cosmic Black Hole Growth and Mass Distribution from Quasar Luminosity Functions at z>4: Implications for Faint and Low-mass Populations in JWST Published: 6/9/2023 9:00:23 PM Updated: 4/30/2024 11:26:44 AM

Paper abstract: The evolution of the quasar luminosity function (QLF) is fundamental tounderstanding the cosmic evolution of black holes (BHs) through their accretionphases. In the era of the James Webb Space Telescope (JWST), Euclid, and NancyGrace Roman Space Telescope, their unprecedented detection sensitivity and widesurvey area can unveil the low-luminosity quasar and low-mass BH population,and provide new insights into quasar host galaxies. We present a theoreticalmodel describing BH growth from initial seeding at z>20 to z~4,incorporating the duration of accretion episodes, the distribution ofEddington ratios, and the mass dependency of BH accretion rates. Byconstraining the model parameters with the observed QLFs at 4<= z<=6across a wide UV luminosity range (-2910^8~M_\odot,leading to mass saturation at M_\bullet\gtrsim 10^{10}~M_\odot. We predictthe BH mass function down to M_{\bullet}~ 10^6~M_\odot for both unobscuredand obscured quasar populations at 4<= z <= 11, offering a benchmark forfuture observational tests. Our model accounts for the presence of both brightand faint quasars at z>4, including those discovered by JWST. Furthermore,our findings suggest two distinct pathways for the early assembly of theBH-galaxy mass correlation: the population with a BH-to-stellar mass ratio nearthe local value of M_\bullet/M_{*}~eq5\times10^{-3} maintains aproximity to the relation through its evolution via moderate growth, while thepopulation that begins to grow above the local relation accretes mass rapidlyand becomes as overmassive as M_\bullet/M_* ~ 0.01-0.1 by z~ 6.