Time Evolution of Galaxy Scaling Relations in Cosmological Simulations

TL;DR

This paper uses cosmological hydrodynamical simulations to predict the evolution of galaxy scaling relations, showing black hole growth, metallicity changes, and the importance of AGN feedback in massive galaxies.

Contribution

It demonstrates that galaxy scaling relations can be reproduced without assuming co-evolution, and highlights the role of AGN feedback in galaxy evolution.

Findings

Black hole mass--velocity dispersion relation does not evolve.

Stellar metallicity increases significantly from redshift 2 to 1.

AGN feedback is essential for matching observations of massive galaxies at low redshift.

Abstract

We predict the evolution of galaxy scaling relationships from cosmological, hydrodynamical simulations, that reproduce the scaling relations of present-day galaxies. Although we do not assume co-evolution between galaxies and black holes a priori, we are able to reproduce the black hole mass--velocity dispersion relation. This relation does not evolve, and black holes actually grow along the relation from significantly less massive seeds than have previously been used. AGN feedback does not very much affect the chemical evolution of our galaxies. In our predictions, the stellar mass--metallicity relation does not change its shape, but the metallicity significantly increases from $z\sim2$ to $z\sim1$, while the gas-phase mass-metallicity relation does change shape, having a steeper slope at higher redshifts ($z\lesssim3$). Furthermore, AGN feedback is required to reproduce observations of the most massive galaxies at $z\lesssim1$, specifically their positions on the star formation main sequence and galaxy mass--size relation.