A New Approach for Simulating Galaxy Cluster Properties

TL;DR

This paper introduces a novel subgrid model called galcons for simulating galaxy properties within hydrodynamical cosmological simulations, improving the realism of galaxy cluster evolution modeling.

Contribution

The paper presents the development and implementation of galcons, a new physically motivated subgrid model for galaxy inclusion in cluster simulations, with improved control over star formation and feedback effects.

Findings

Galcon simulation yields lower stellar fractions.

Produces larger gas core radius and more isothermal temperature profile.

Results align better with observational data.

Abstract

We describe a subgrid model for including galaxies into hydrodynamical cosmological simulations of galaxy cluster evolution. Each galaxy construct- or galcon- is modeled as a physically extended object within which star formation, galactic winds, and ram pressure stripping of gas are modeled analytically. Galcons are initialized at high redshift (z~3) after galaxy dark matter halos have formed but before the cluster has virialized. Each galcon moves self-consistently within the evolving cluster potential and injects mass, metals, and energy into intracluster (IC) gas through a well-resolved spherical interface layer. We have implemented galcons into the Enzo adaptive mesh refinement code and carried out a simulation of cluster formation in a LambdaCDM universe. With our approach, we are able to economically follow the impact of a large number of galaxies on IC gas. We compare the results of the galcon simulation with a second, more standard simulation where star formation and feedback are treated using a popular heuristic prescription. One advantage of the galcon approach is explicit control over the star formation history of cluster galaxies. Using a galactic SFR derived from the cosmic star formation density, we find the galcon simulation produces a lower stellar fraction, a larger gas core radius, a more isothermal temperature profile, and a flatter metallicity gradient than the standard simulation, in better agreement with observations.