A 10-Billion-Year View of Supermassive Black Hole Growth and Accretion

Supermassive black holes (SMBHs) sit at the centers of nearly all galaxies, yet their growth and appearance can vary depending on their intrinsic properties and our viewing angle. A central question is what controls the gas and dust surrounding these black holes. Studies in the local Universe suggest that the accretion rate—the rate at which a black hole feeds—is the key factor. Here, we extend this investigation to earlier cosmic times to test whether this trend persists across SMBH evolution. We analyze 2,293 X-ray–selected SMBHs from the Stripe82X survey, with spectroscopic mass measurements and obscuration estimates. Using Bayesian Markov Chain Monte Carlo modeling, we trace the evolution of mass and accretion rate distributions over the past 10 billion years (z ≲ 2). We find that while SMBHs of different masses accrete similarly today, lower-mass SMBHs grew more rapidly in the past, indicating a mass-dependent growth history.