Exploring the halo occupation distribution for moderate X-ray luminosity active galactic nuclei in the EAGLE cosmological simulation

TL;DR

This study uses the EAGLE simulation to model the Halo Occupation Distribution of moderate X-ray luminosity AGN, revealing that minor mergers are the main trigger across various redshifts.

Contribution

It extends previous dark matter-based models by incorporating hydrodynamical simulation data to analyze AGN occupation and merger-triggering mechanisms.

Findings

Minor mergers are the dominant trigger for mXAGN.

HOD varies with redshift from 2 to present.

Results support merger-driven AGN activation models.

Abstract

The hydrodynamical cosmological simulation \eagle{} is used to model the Halo Occupation Distribution (HOD) of moderate X-ray luminosity active galactic nuclei (mXAGN), extending previous work using only dark matter simulations and empirical relations. By examining mergers as a triggering mechanism, we focus on halos typical of galaxy groups and cluster-like systems with masses $\geq 10^{12.75}\,{\rm M}{\odot}\,h^{-1}$. We analyze simulation data to create catalogs of central and satellite galaxies. We study their merger history we quantify the percentage of minor and major mergers in the mXAGN sample. We obtain the HOD for central and satellite mXAGN across a redshift interval from \(z=2\) to the present epoch. Our results indicate that, across most redshifts, minor mergers slightly predominate as the primary mechanism for triggering mXAGN.