The dearth of difference between central and satellite galaxies II. Comparison of observations with L-GALAXIES and EAGLE in star formation quenching

TL;DR

This study compares galaxy quenching trends in observations with predictions from the L-GALAXIES semi-analytic model and the EAGLE hydrodynamical simulation, revealing significant discrepancies in L-GALAXIES.

Contribution

It demonstrates that L-GALAXIES fails to reproduce observed quenched galaxy trends, while EAGLE aligns well with observational data, highlighting differences in feedback process modeling.

Findings

L-GALAXIES overpredicts quenched centrals at certain halo masses.

EAGLE accurately reproduces the similarity in quenched fractions of centrals and satellites.

Group finder effects on galaxy classification are assessed.

Abstract

As we demonstrated in Paper I, the quenched fractions of central and satellite galaxies as function of halo mass are extremely similar, as long as one controls for stellar mass. The same holds for the quenched fractions as a function of central velocity dispersion, which is tightly correlated with black hole mass, as long as one controls for both stellar and halo mass. Here we use mock galaxy catalogs constructed from the latest semi-analytic model, L-GALAXIES, and the state-of-the-art hydrodynamical simulation, EAGLE, to investigate whether these models can reproduce the trends seen in the data. We also check how the group finder used to identify centrals and satellites impacts our results. We find that L-GALAXIES fails to reproduce the trends. The predicted quenched fraction of central galaxies increases sharply with halo mass around $10^{12.5}h^{-1}M_{\odot}$ and with black hole mass around $\sim10^{6.5}M_{\odot}$, while the predicted quenched fraction of satellites increases with both halo and black hole masses gradually. In contrast, centrals and satellites in EAGLE follow almost the same trend as seen in the data. We discuss the implications of our results for how feedback processes regulate galaxy quenching.