The role of black hole feedback on galaxy star formation and the degeneracy with halo quenching

TL;DR

This study uses a semi-empirical model to explore how SMBH feedback influences galaxy quenching, finding that SMBH growth and halo quenching effects are degenerate in explaining observed galaxy properties.

Contribution

The paper introduces DECODE, a data-driven semi-empirical model linking SMBH growth to galaxy star formation and quenching, highlighting degeneracies with halo quenching.

Findings

Imposing the $M_{\rm BH} - \sigma_\star$ relation can reproduce observed galaxy quenched fractions.

The model predicts SMBH scaling relations consistent with observations across redshifts.

SMBH accretion peaks within 1 Gyr of host galaxy star formation histories.

Abstract

The interplay between the accretion of supermassive black holes (SMBHs) and the stellar mass growth of the host galaxies is still a matter of hot debate. The accretion of the SMBHs is expected to release energy under the form of AGNs. This energy is believed to impact the star formation activity and contribute to the quenching of galaxies. Here, we address this key unsolved issue with our cosmological semi-empirical model DECODE. In DECODE, we grow galaxies with their SFR linked to halo accretion rate distributions via abundance matching. SMBHs are evolved following the stellar mass growth of their host galaxies by assigning an accretion rate at each redshift from the empirical Eddington ratio distributions and duty cycles. We test the assumption that galaxies permanently quench when their central SMBHs approach the limit imposed by the observed $M_{\rm BH} - \sigma_\star$ relation, as a proxy of SMBH disruptive feedback. We find that simply imposing the $M_{\rm BH} - \sigma_\star$ condition is sufficient to generate a fraction of quenched galaxies consistent with current data, including the newest ones from Euclid. In addition, our minimal, data-driven model, also predicts SMBH scaling relations consistent in slope and normalisation with those observed, and an $M_{\rm BH} - M_\star$ relation weakly evolving with redshift. The model also naturally generates SMBH accretion rates peaking within 1 Gyr of their host SFHs. We note that all the main predictions on galaxy quenched fractions and SMBH growth histories and scaling relations are degenerate with those expected in a halo quenching model. The comprehensive data-driven model presented in this work represents an invaluable tool to investigate SMBH demography across time and environments in an accurate, physically motivated manner, ideally suited to rapidly explore the implications from large surveys, such as Euclid and Rubin-LSST.