No significant evolution of relations between Black hole mass and Galaxy total stellar mass up to z~2.5

TL;DR

This study finds that the ratio of black hole mass to galaxy stellar mass remains roughly constant up to redshift 2.5, indicating no significant evolution in this relation over cosmic time.

Contribution

It provides the first comprehensive analysis of the MBH-Mstellar relation up to z~2.5 using a large, uniformly measured sample of AGNs from the COSMOS survey.

Findings

No significant evolution of MBH/Mstellar ratio up to z~2.5

Black hole-to-host stellar mass ratio remains around 0.3% across redshifts

Results are consistent with the local universe relation

Abstract

We investigate the cosmic evolution of the ratio between black hole mass (MBH) and host galaxy total stellar mass (Mstellar) out to z~2.5 for a sample of 100 X-ray-selected moderate-luminosity, broad-line active galactic nuclei (AGNs) in the Chandra-COSMOS Legacy Survey. By taking advantage of the deep multi-wavelength photometry and spectroscopy in the COSMOS field, we measure in a uniform way the galaxy total stellar mass using a SED decomposition technique and the black hole mass based on broad emission line measurements and single-epoch virial estimates. Our sample of AGN host galaxies has total stellar masses of 10^10-12Msun, and black hole masses of 10^7.0-9.5Msun. Combining our sample with the relatively bright AGN samples from the literature, we find no significant evolution of the MBH-Mstellar relation with black hole-to-host total stellar mass ratio of MBH/Mstellar~0.3% at all redshifts probed. We conclude that the average black hole-to-host stellar mass ratio appears to be consistent with the local value within the uncertainties, suggesting a lack of evolution of the MBH-Mstellar relation up to z~2.5.