A new RASS galaxy cluster catalogue with low contamination extending to z~1 in the DES overlap region. (2019)
Keywords :
galaxies clusters: general - galaxies: clusters: intracluster medium - galaxies: distances and redshifts
Abstract:We present the MARD-Y3 catalogue of between 1086 and 2171 galaxy clusters (52 per cent and 65 per cent new) produced using multicomponent matched filter (MCMF) follow-up in 5000 deg^2^ of DES-Y3 optical data of the ~20000 overlapping ROSAT All-Sky Survey source catalogue (2RXS) X-ray sources. Optical counterparts are identified as peaks in galaxy richness as a function of redshift along the line of sight towards 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 per cent and 9.6 per cent for the cuts adopted here. For each cluster we
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This is the MARD-Y3 catalog. X-ray selected, optically confirmed
cluster catalog (see abstract and paper). The intput X-ray catalog is
the RASS based 2RXS catalog (Boller+16). Entries from RA_DEG to EXI_ML
are taken from 2RXS. Names are based on 2RXS but the first 3 letters
are replaced by MARD (Multi-component mAtch filter confirmed RASS
sources using DES data. MCMF keeps up to three counterparts P1..P3)
per X-ray candidate. entries ending with _P1.._P3 correspond to the
different peaks. Entries ending in _LFCR show the counter part with
the lowest f_cont, therefore most likely counterpart.
F_cont provides a measure of the contamination fraction caused by
random superpositions. A catalog is expected to have a contamination
fraction of X when clusters are selected as f_cont<=X.
he full catalog provided here is cut at f_cont_LFCR<=0.2 and therefore
allows for 20% residual contamination by chance super positions
between 2RXS source and optical counter part. The X-ray source
detection tends to detect large extended sources as multiple sources.
We therefore suggest to exclude multiple detections by selection
MULTIPLE_FLAG=0, the most likely counter part will remain in the
sample but sourrounding multiples will be excluding. Remaining
contamination can be reduced by selecting D_SIG_LFCR<2 (sigma), which
excludes candidates with a reasonable WISE counterpart in NWAY and
differs more than 2 sigma high (too high luminosity given richness)
from the mean luminosity richness relation. DFC_LFCR provides the
difference between lowest and second lowest f_cont of the X-ray
source. This allows to identify cases with multiple counter parts at
different redshifts.
Matthias Klein, matthias.klein(at)physik.lmu.de
