A New RASS Galaxy Cluster Catalog with Low Contamination Extending to $zsim1$ in the DES Overlap Region. (arXiv:1812.09956v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Klein_M/0/1/0/all/0/1">Matthias Klein</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grandis_S/0/1/0/all/0/1">Sebastian Grandis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mohr_J/0/1/0/all/0/1">Joseph Mohr</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Paulus_M/0/1/0/all/0/1">Maria Paulus</a>, the <a href="http://arxiv.org/find/astro-ph/1/au:+Collaboration_DES/0/1/0/all/0/1">DES Collaboration</a>

We present the MARD-Y3 catalog of between 1086 and 2171 galaxy clusters
produced using multi-component matched filter (MCMF) followup in $5000
~mathrm{deg}^2$ of DES-Y3 optical data of the ~20000 2RXS X-ray sources. MCMF
is used to identify optical counterparts 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
$f_mathrm{cont}$ of being a random superposition $f_mathrm{cont}$ is
extracted from the galaxy richness distributions along large numbers of random
lines of sight, and the catalog size depends on the $f_mathrm{cont}$ cuts. The
catalog covers a redshift range of 0.020.5$, and it has residual contamination of between 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 and estimators of dynamical state.
The cluster photometric redshifts are high quality with $sigma_{Delta
z/(1+z)}=0.0046$. Using coincidence with NWAY infrared sources, we develop a
method for excluding ~50% of remaining random superpositions from the catalog
and show that ~1% of clusters exhibit evidence of X-ray luminosity boosting
from emission by cluster AGN. Extensive comparison with other cluster catalogs
(MCXC, RM, SPT-SZ, Planck) is performed to test consistency. We measure the
cluster X-ray luminosity function and compare it to the expectation from a
fiducial cosmology and externally calibrated luminosity- and richness-mass
relations with intrinsic scatter. Agreement is good, providing evidence that
the MARD-Y3 sample 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.

We present the MARD-Y3 catalog of between 1086 and 2171 galaxy clusters
produced using multi-component matched filter (MCMF) followup in $5000
~mathrm{deg}^2$ of DES-Y3 optical data of the ~20000 2RXS X-ray sources. MCMF
is used to identify optical counterparts 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
$f_mathrm{cont}$ of being a random superposition $f_mathrm{cont}$ is
extracted from the galaxy richness distributions along large numbers of random
lines of sight, and the catalog size depends on the $f_mathrm{cont}$ cuts. The
catalog covers a redshift range of 0.02<z<1.1 with more than 100 clusters at
$z>0.5$, and it has residual contamination of between 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 and estimators of dynamical state.
The cluster photometric redshifts are high quality with $sigma_{Delta
z/(1+z)}=0.0046$. Using coincidence with NWAY infrared sources, we develop a
method for excluding ~50% of remaining random superpositions from the catalog
and show that ~1% of clusters exhibit evidence of X-ray luminosity boosting
from emission by cluster AGN. Extensive comparison with other cluster catalogs
(MCXC, RM, SPT-SZ, Planck) is performed to test consistency. We measure the
cluster X-ray luminosity function and compare it to the expectation from a
fiducial cosmology and externally calibrated luminosity- and richness-mass
relations with intrinsic scatter. Agreement is good, providing evidence that
the MARD-Y3 sample 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.

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