A Preferential Growth Channel for Supermassive Black Holes in Elliptical Galaxies at z ? 2

The assembly of stellar and supermassive black hole (SMBH) mass in elliptical galaxies since $z\sim1$ can help to diagnose the origins locally-observed correlations between SMBH mass. We therefore construct three samples galaxies, one at $z\sim0$ two $0.7\lesssim z \lesssim2.5$, quantify their relative positions $M_{BH}-M_*$ plane. Using a Bayesian analysis framework, we find evidence for translational offsets both local sample higher redshift samples. are small, consistent with measurement bias, but much larger, reaching factor seven $z\sim0$. magnitude offset may also depend on redshift, $\sim20$ $z\sim 2$. result is robust against variation high low changes approach. evolution challenging explain terms selection biases. conclude that either there physical mechanism preferentially grows SMBHs $z\lesssim 2$, or biases underestimated, redshift.