Constructing a Galaxy Cluster Catalog in IllustrisTNG-300 using the Mulguisin Algorithm

TL;DR

This paper introduces a new galaxy cluster catalog from the IllustrisTNG-300 simulation using the Mulguisin algorithm, which identifies clusters based on galaxy overdensities, providing a more observationally comparable catalog.

Contribution

The paper presents the Mulguisin algorithm for galaxy cluster identification, offering a refined catalog that separates galaxy overdensities and improves upon the FoF method.

Findings

MGS catalog lists 303 halos with M$_{200} > 10^{14}$ M$_{\odot}$, about 10% more than FoF.

MGS identifies more systems by separating independent halos bundled in FoF.

The catalog enables better study of galaxy evolution and merging clusters.

Abstract

We present a new simulated galaxy cluster catalog based on the IllustrisTNG simulation. We use the Mulguisin (MGS) algorithm to identify galaxy overdensities. Our cluster identification differs from the previous FoF cluster identification in two aspects; 1) we identify cluster halos based on the galaxy subhalos instead of unobservable dark matter particles, and 2) we use the MGS algorithm that separates galaxy overdensities hosted by massive galaxies. Our approach provides a cluster catalog constructed similar to the observed cluster catalogs using spectroscopic surveys. The MGS cluster catalog lists 303 halos with M$_{200} > 10^{14}$ M$_{\odot}$, including $\sim 10\%$ more than the FoF. The MGS catalog includes more systems because we separate some independent massive MGS cluster halos that are bundled into a single FoF algorithm. These independent MGS halos are apparently distinguishable in galaxy spatial distribution and the phase-space diagram. Because we constructed a refined cluster catalog that identifies local galaxy overdensities, we evaluate the effect of MGS clusters on the evolution of galaxies better than using the FoF cluster catalog. The MGS halo identification also enables effective identifications of merging clusters by selecting systems with neighboring galaxy overdensities. We thus highlight that the MGS cluster catalog is a useful tool for studying clusters in cosmological simulations and for comparing with the observed cluster samples.