Galactic Correlates of Supermassive Black Hole Growth and Their Application, Astronomy Colloquium, Niel Brandt, Penn State
2025-04-24 20:30 - 21:30 UTC | 4421 Sterling Hall
The co-evolution of supermassive black holes (SMBHs) and galaxies can be effectively constrained through sample-based analyses of the galactic correlates of long-term SMBH growth. Relevant correlates include galaxy stellar mass (M*), star formation rate (SFR), and compactness. The sample-averaged SMBH accretion rate (BHAR), which constrains long-term SMBH growth in galaxy populations of interest, is statistically measured using data from sensitive X-ray surveys including the Chandra Deep Fields, XMM-SERVS, COSMOS, and eFEDS. We have been advancing such investigations using partial-correlation analyses and complete, high-quality samples now reaching 8100 AGNs in 1.3 million galaxies, and I will briefly summarize some key findings. Specifically, (1) for the general galaxy population at z = 0.1-4, SMBH growth correlates most strongly with M*; (2) for bulge-dominated systems, a strong BHAR-SFR correlation is observed, indicating synchronized growth between SMBHs and bulges; (3) BHAR also clearly correlates with galaxy compactness among star-forming galaxies, likely due to enhanced nuclear gas density for compact galaxies. Furthermore, combining these empirical correlations with large-scale numerical simulations of galaxy evolution enables improved tracking of SMBH growth through accretion and mergers across cosmic history. This approach provides insights into the evolution of the SMBH mass function, the SMBH mass-M* scaling relation, the relative importance of accretion and mergers to overall SMBH growth, and long-lived wandering SMBHs.
