Stellar populations across the black hole mass - velocity dispersion relation

TL;DR

This study investigates the relationship between supermassive black hole mass and stellar populations in galaxies, revealing that over-massive black holes correlate with older, alpha-enhanced stars, suggesting AGN feedback influences galaxy evolution.

Contribution

It provides new observational evidence linking black hole mass to stellar population properties, emphasizing the role of AGN feedback in galaxy evolution.

Findings

Over-massive BH galaxies are older and more alpha-enhanced.

Lower scatter in BH mass-{ }Fe plane compared to standard relation.

Active galactic nucleus feedback impacts star formation histories.

Abstract

Coevolution between supermassive black holes (BHs) and their host galaxies is universally adopted in models for galaxy formation. In the absence of feedback from active galactic nuclei, simulated massive galaxies keep forming stars in the local Universe. From an observational point of view, however, such coevolution remains unclear. We present a stellar population analysis of galaxies with direct BH mass measurements and the BH mass-{\sigma} relation as a working framework. We find that over-massive BH galaxies, i.e., galaxies lying above the best-fitting BH mass-{\sigma} line, tend to be older and more {\alpha}-element enhanced than under-massive BH galaxies. The scatter in the BH mass-{\sigma}-[{\alpha}/Fe] plane is significantly lower than in the standard BH mass-{\sigma} relation. We interpret this trend as an imprint of active galactic nucleus feedback on the star formation histories of massive galaxies.