Total density profile of massive early-type galaxies in Horizon-AGN simulation: impact of AGN feedback and comparison with observations

TL;DR

This study uses cosmological simulations to analyze how AGN feedback influences the total density profiles of massive early-type galaxies, showing that including AGN feedback improves agreement with observations and affects the correlation with dark matter and stellar components.

Contribution

It demonstrates the significant impact of AGN feedback on galaxy density profiles and compares simulation results with observational data, highlighting the importance of AGN in galaxy evolution models.

Findings

AGN feedback improves agreement with observed density profiles.

Inclusion of AGN feedback correlates total density slope with dark matter slope.

Without AGN, simulated galaxies are too extended and have higher density slopes.

Abstract

Using the two large cosmological hydrodynamical simulations, Horizon-AGN (H-AGN) and Horizon-noAGN (H-noAGN, no AGN feedback), we investigate how a typical sub-grid model for AGN feedback affects the evolution of the total density profiles (dark matter + stars) at the effective radius of massive early-type galaxies (M*>10^11 Msun). We have studied the dependencies of the mass-weighted density slope gamma'_tot with the effective radius, the galaxy mass and the host halo mass at z~0.3 and found that the inclusion of AGN feedbackalways leads to a much better agreement with observational values and trends. Our analysis suggests also that the inclusion of AGN feedback favours a strong correlation between gamma'_tot and the density slope of the dark matter component while, in the absence of AGN activity, gamma'_tot is rather strongly correlated with the density slope of the stellar component. Finally, we find that gamma'_tot derived from our samples of galaxies increases from z=2 to z=0,in good agreement with the expected observational trend. The derived slopes are slightly lower than in the data when AGN is included because the simulated galaxies tend to be too extended, especially the least massive ones. However, the simulated compact galaxies without AGN feedback have gamma'_tot values that are significantly too high compared to observations.