Galaxy and black hole coevolution in dark matter haloes not captured by cosmological simulations

TL;DR

This study compares observed AGN host galaxy properties with cosmological simulations, revealing significant discrepancies in galaxy and black hole coevolution modeling, highlighting the need for improved physics in simulations.

Contribution

It provides a comprehensive observational benchmark for AGN host galaxies and critically evaluates the performance of leading cosmological simulations in reproducing these observations.

Findings

Simulations fail to match observed trends in star formation and quiescence.

All simulations overproduce quenched low-mass satellites in massive halos.

Discrepancies in quenched fractions of massive centrals and low-density environments.

Abstract

Star formation in galaxies is governed by internal and environmental processes, yet their relative roles are not well understood. In particular, uncertainties in measurements of active galactic nuclei (AGN) host galaxies, combined with modeling limitations, obfuscate the impact of supermassive black hole feedback across environments and over time. Here we address this with a comprehensive analysis of ~60,000 nearby AGNs (z < 0.15 and new environment and halo-mass measurements for ~500,000 AGN and non-AGN host galaxies. This benchmark enables unified comparisons with three prominent cosmological simulations--SIMBA, TNG, and EAGLE--and reveals major, contrasting shortcomings. Simulations fail to reproduce observed trends linking star formation, quiescence, AGN luminosity, stellar mass, and halo mass. While simulations qualitatively capture that AGNs are more common in low-mass halos than in rich groups or clusters, detailed host demographics diverge strongly from observations. Partial agreement exists in the stellar mass distribution within large-scale structures, yet all simulations overproduce quenched low-mass satellites in massive halos, while misrepresenting quenched fractions of massive central galaxies and those in low-density environments, which are sensitive to feedback implementation. Improved AGN physics and modeling of multi-phase gas cooling and flows are required to capture the observed interplay between black holes, galaxies, and halos.