NIHAO XXVIII: Collateral effects of AGN on dark matter concentration and stellar kinematics

TL;DR

This study demonstrates that AGN feedback significantly influences dark matter concentration and stellar kinematics in galaxies, aligning simulations more closely with observations and highlighting its crucial role in galaxy formation models.

Contribution

The paper provides new insights into how AGN feedback affects dark matter profiles and stellar rotation, improving the realism of galaxy simulations compared to previous models.

Findings

AGN feedback reduces central density in massive galaxies.

AGN feedback aligns simulated concentration-mass relation with observations.

AGN feedback influences the distribution of slow and fast rotators.

Abstract

Although active galactic nuclei (AGN) feedback is required in simulations of galaxies to regulate star formation, further downstream effects on the dark matter distribution of the halo and stellar kinematics of the central galaxy can be expected. We combine simulations of galaxies with and without AGN physics from the Numerical Investigation of a Hundred Astrophysical Objects (NIHAO) to investigate the effect of AGN on the dark matter profile and central stellar rotation of the host galaxies. Specifically, we study how the concentration-halo mass ($c-M$) relation and the stellar spin parameter ($\lambda_R$) are affected by AGN feedback. We find that AGN physics is crucial to reduce the central density of simulated massive ($\gtrsim 10^{12}$ M$_\odot$) galaxies and bring their concentration to agreement with results from the Spitzer Photometry & Accurate Rotation Curves (SPARC) sample. Similarly, AGN feedback has a key role in reproducing the dichotomy between slow and fast rotators as observed by the ATLAS$^{3\text{D}}$ survey. Without star formation suppression due to AGN feedback, the number of fast rotators strongly exceeds the observational constraints. Our study shows that there are several collateral effects that support the importance of AGN feedback in galaxy formation, and these effects can be used to constrain its implementation in numerical simulations.