BASS. XXXVI. Constraining the Local Supermassive Black Hole - Halo Connection with BASS DR2 AGN

TL;DR

This study uses clustering statistics and luminosity functions from BASS DR2 to examine the relationship between supermassive black holes and their host dark matter halos, finding a significant correlation with halo mass.

Contribution

It provides the first empirical evidence supporting a tight correlation between SMBH mass and dark matter halo mass in the local universe.

Findings

The SMBH-halo mass correlation model is preferred at 1.8σ significance.

Including independent black hole mass measurements increases the preference to 4.6σ.

Clustering differences on 1-halo scales support the SMBH-halo connection.

Abstract

We investigate the connection between supermassive black holes (SMBHs) and their host dark matter halos in the local universe using the clustering statistics and luminosity function of AGN from the Swift/BAT AGN Spectroscopic survey (BASS DR2). By forward-modeling AGN activity into snapshot halo catalogs from N-body simulations, we test a scenario in which SMBH mass correlates with dark matter (sub)halo mass for fixed stellar mass. We compare this to a model absent of this correlation, where stellar mass alone determines the SMBH mass. We find that while both simple models are able to largely reproduce the abundance and overall clustering of AGN, the model in which black hole mass is tightly correlated with halo mass is preferred by the data by $1.8\sigma$. When including an independent measurement on the black hole mass-halo mass correlation, this model is preferred by $4.6\sigma$. We show that the clustering trends with black hole mass can further break the degeneracies between the two scenarios, and that our preferred model reproduces the measured clustering differences on 1-halo scales between large and small black hole masses. These results indicate that the halo binding energy is fundamentally connected to the growth of supermassive black holes.