The relation between black hole spin, star formation rate, and black hole mass for supermassive black holes

¹ College of Physics and Electronic Engineering, Qujing Normal University, Qujing 655011, PR China
² School of Astronomy and Space Science, Nanjing University, Nanjing 210093, PR China
³ Center for Astrophysics, Guangzhou University, Guangzhou 510006, China
⁴ Anqing Normal University, 246133 Anqing, PR China
⁵ Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, China
⁶ School of Physical Science and Technology, Kunming University, 650214 Kunming, PR China

^⋆ Corresponding authors; ynkmcyy@yeah.net, qsgu@nju.edu.cn

Received: 18 October 2024
Accepted: 14 January 2025

Abstract

Both theoretical models and observational evidence indicate that jets and/or outflows driven by central active supermassive black holes exert a significant feedback effect on the overall properties of their host galaxies. Theoretical models suggest that the spin of supermassive black holes drives relativistic jets. Therefore, we investigate the relationship between black hole spin, star formation rate, and black hole mass using a sample of 48 low-redshift supermassive black holes. By performing multiband fitting of spectral energy distribution, we derive the star formation rates and stellar masses of the host galaxies harbouring these supermassive black holes. Our main results are as follows: (i) For black holes with masses M_BH ≲ 10^6.5 M_⊙, the spin increases with increasing black hole mass, suggesting that black hole growth is primarily driven by gas accretion, particularly in the coherent gas accretion regime. Conversely, for black holes with masses M_BH ≳ 10^7.5 M_⊙, the spin decreases with increasing black hole mass, indicating that growth occurs mainly through mergers, inducing chaotic accretion. (ii) At low star formation rates, black hole spin increases with increasing star formation rates, consistent with gas accretion. However, at high star formation rates, black hole spin decreases with increasing star formation rates, suggesting black hole mergers. The value of the black hole spin may be used to diagnose the star formation rate of the host galaxies through active galactic nuclei activities. (iii) Our data and analysis confirm the well-known relation between stellar mass and black hole mass, with the fitting function log M_BH = 0.57log M_* + 1.94.