Accretion Efficiency Evolution of Central Supermassive Black Holes in Quasars

Arta Khosravi, Alireza Karamzadeh, Seyed Sajad Tabasi, Javad T. Firouzjaee

Published 2024-05-06Version 1

The ongoing debate regarding the most accurate accretion model for supermassive black holes at the center of quasars has remained a contentious issue in astrophysics. One significant challenge is the variation in calculated accretion efficiency, with values exceeding the standard range of $0.038 < \epsilon < 0.42$. This discrepancy is especially pronounced in high redshift supermassive black holes, necessitating the development of a comprehensive model that can address the accretion efficiency for supermassive black holes in both the low and high redshift ranges. In this study, we have focused on low redshift ($z < 0.5$) PG quasars (79 quasars) and high redshift ($z \geq 3$) quasars with standard disks from the flux- and volume-limited QUOTAS+QuasarNET dataset (76 quasars) to establish a model for accretion efficiency. An interesting trend is revealed where in redshift larger than 3, accretion efficiency increases as redshift decreases, while in redshift lower than 0.5, accretion efficiency decreases with reducing redshift. This suggests a peak in accretion efficiency between the low and high redshift quasars. This peak is recognized for the flux- and volume-limited QUOTAS+QuasarNET+DL11 dataset, which is $z \sim 2.675$, and it seems to be related to the peak of the star formation rate. ($1 < z_{SFR} < 3$). This result can potentially lead to a more accurate correlation between the star formation rate in quasars and their relationship with the mass of the central supermassive black holes with a more comprehensive disk model in future studies.