# A New RASS Galaxy Cluster Catalog with Low Contamination Extending to $z\sim1$ in the DES Overlap Region

## TL;DR

The paper introduces the MARD-Y3 galaxy cluster catalog from DES-Y3 data, achieving low contamination and extending to redshift ~1, with detailed cluster properties and validation against other surveys.

## Contribution

It presents a new galaxy cluster catalog using a multi-component matched filter method, with improved contamination control and comprehensive cluster property measurements.

## Key findings

- Low residual contamination of 2.6% and 9.6% for selected cuts.
- High-quality photometric redshifts with σ=0.0046.
- Good agreement with external cluster catalogs and models.

## Abstract

We present the MARD-Y3 catalog of between 1086 and 2171 galaxy clusters (52\% and 65\% new) produced using multi-component matched filter (MCMF) followup in 5000\,deg$^2$ of DES-Y3 optical data of the $\sim$20000 overlapping 2RXS X-ray sources. Optical counterparts are identified as peaks in galaxy richness as a function of redshift along the line of sight toward each 2RXS source within a search region informed by an X-ray prior. All peaks are assigned a probability \fcont\ of being a random superposition. The clusters lie at $0.02<z<1.1$ with more than 100 clusters at $z>0.5$. Residual contamination is 2.6\% and 9.6\% for the cuts adopted here. For each cluster we present the optical center, redshift, rest frame X-ray luminosity, $M_{500}$ mass, coincidence with NWAY infrared sources and estimators of dynamical state. About 2\% of MARD-Y3 clusters have multiple possible counterparts, the photo-z's are high quality with $\sigma_{\Delta z/(1+z)}=0.0046$, and $\sim$1\% of clusters exhibit evidence of X-ray luminosity boosting from emission by cluster AGN. Comparison with other catalogs (MCXC, RM, SPT-SZ, Planck) is performed to test consistency of richness, luminosity and mass estimates. We measure the MARD-Y3 X-ray luminosity function and compare it to the expectation from a fiducial cosmology and externally calibrated luminosity- and richness-mass relations. Agreement is good, providing evidence that MARD-Y3 has low contamination and can be understood as a simple two step selection-- X-ray and then optical-- of an underlying cluster population described by the halo mass function.