A Correlation Between Black Hole Mass and Dark Matter Halo Concentration in Cosmological Simulations

TL;DR

This study reveals a positive correlation between supermassive black hole mass and dark matter halo concentration in cosmological simulations, highlighting the role of halo structure in black hole growth and galaxy evolution.

Contribution

It demonstrates a significant correlation in certain simulations and links it to accretion models, advancing understanding of black hole and galaxy coevolution.

Findings

Positive correlation in TNG, EAGLE, CAMELS-TNG simulations

No correlation in SIMBA simulation with torque-limited accretion

Mass-dependent sign change of correlation at log(M200/Msun) ≈ 11.5

Abstract

We report the discovery of a positive correlation between supermassive black hole mass and dark matter halo concentration at fixed halo mass in cosmological hydrodynamical simulations. Analyzing central galaxies in TNG100 (N = 18,954), EAGLE (N = 1,522), and CAMELS-TNG (N = 6,664), we find partial correlation coefficients of r = +0.24, +0.34, and +0.66 respectively, all highly significant (p < 10^-10). The correlation is absent in SIMBA (r = +0.01, p = 0.09), which employs a torque-limited black hole accretion model rather than the Bondi-based prescription used by the other simulations. Both TNG and EAGLE exhibit a mass-dependent sign transition: the correlation is negative or null at log(M200/Msun) < 11.5 but strongly positive at higher masses. We interpret this pattern as reflecting the coupling between Bondi accretion rates and central gas density structure: halos with higher concentration have denser cores, enabling more efficient black hole growth at fixed halo mass. The absence of the correlation in torque-limited models supports this interpretation. These results suggest that halo concentration may be a fundamental parameter governing black hole-galaxy coevolution.