J/MNRAS/474/3324 Multicomponent matched filter test (Klein+, 2018)
A multicomponent matched filter cluster confirmation tool for eROSITA:
initial application to the RASS and DES-SV data sets.
Klein M., Mohr J.J., Desai S., Israel H., Allam S., Benoit-levy A.,
Brooks D., Buckley-Geer E., Carnero Rosell A., Carrasco Kind M.,
Cunha C.E., da Costa L.N., Dietrich J.P., Eifler T.F., Evrard A.E.,
Frieman J., Gruen D., Gruendl R.A., Gutierrez G., Honscheid K., James D.J.,
Kuehn K., Lima M., Maia M.A.G., March M., Melchior P., Menanteau F.,
Miquel R., Plazas A.A., Reil K., Romer A.K., Sanchez E., Santiago B.,
Scarpine V., Schubnell M., Sevilla-Noarbe I., Smith M., Soares-Santos M.,
Sobreira F., Suchyta E., Swanson M.E.C., Tarle G., (the Des Collaboration)
<Mon. Not. R. Astron. Soc., 474, 3324-3343 (2018)>
=2018MNRAS.474.3324K 2018MNRAS.474.3324K (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Galaxies ; X-ray sources ; Redshifts
Keywords: galaxies: clusters: general -
galaxies: clusters: intracluster medium -
galaxies: distances and redshifts - X-rays: galaxies: clusters
Abstract:
We describe a multicomponent matched filter (MCMF) cluster
confirmation tool designed for the study of large X-ray source
catalogues produced by the upcoming X-ray all-sky survey mission
eROSITA. We apply the method to confirm a sample of 88 clusters with
redshifts 0.05<z<0.8 in the recently published 2RXS catalogue from
the ROSAT All-Sky Survey (RASS) over the 208 deg2 region overlapped
by the Dark Energy Survey (DES) Science Verification (DES-SV) data
set. In our pilot study, we examine all X-ray sources, regardless of
their extent. Our method employs a multicolour red sequence (RS)
algorithm that incorporates the X-ray count rate and peak position in
determining the region of interest for follow-up and extracts the
positionally and colour-weighted optical richness λMCMF as a
function of redshift for each source. Peaks in the
λMCMF-redshift distribution are identified and used to
extract photometric redshifts, richness and uncertainties. The
significances of all optical counterparts are characterized using the
distribution of richnesses defined along random lines of sight. These
significances are used to extract cluster catalogues and to estimate
the contamination by random superpositions of unassociated optical
systems. The delivered photometric redshift accuracy is
δz/(1+z)=0.010. We find a well-defined X-ray
luminosity-λMCMF relation with an intrinsic scatter of
δln(λMCMF|Lx)=0.21. Matching our catalogue with the
DES-SV redMaPPer catalogue yields good agreement in redshift and
richness estimates; comparing our catalogue with the South Pole
Telescope (SPT) selected clusters shows no inconsistencies. SPT
clusters in our data set are consistent with the high-mass extension
of the RASS-based λMCMF-mass relation.
Description:
The DES-SV data were acquired between 2012 November 1 and 2013 February.
In total, we use 225 tiles in the SPT-East region and in total have
208.7 deg2 of unmasked area. We combine all individual tile
catalogues and exclude multiple entries in the overlapping regions.
Similarly to Hennig et al. (2017MNRAS.467.4015H 2017MNRAS.467.4015H), we
separate galaxies from stars on the bright end by excluding all
objects with spread_model less than 0.0025. This cut allows a clean
separation between galaxies and stars down to i∼22mag.
Below this magnitude, we attempt no stellar exclusion using object
morphology. In this work, we adopt a more conservative limit in i band
that is derived for each tile by measuring where the catalogue number
density per magnitude starts to continuously fall below a best-fitting
power law that was fitted to the region 19≤i≤21.
Characteristically, this limit lies between i=22.2 and 22.7.
Our aim is the identification of X-ray-selected galaxy clusters from
the 2RXS catalogue (Boller et al. 2016A&A...588A.103B 2016A&A...588A.103B, Cat.
J/A+A/588/A103).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 108 89 *List of all 2RXS clusters with at least one peak
in redshift exceeding Pλ and Ps>0.98
and P*<0.1.
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Note on table1.dat: Multiple X-ray associations with the same optical cluster
are excluded. Only the parameters related to the two peaks with highest value
in Pλ are shown.
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See also:
J/A+A/588/A103 : Second ROSAT all-sky survey (2RXS) source catalog
(Boller+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Name (2RXC JHHMM.m+DDMM)
19- 25 F7.4 deg RAdeg Right ascension (J2000)
27- 34 F8.4 deg DEdeg Declination (J2000)
36- 40 F5.3 --- Pl1 Probability of obtaining a particular richness
λMCMF as a function of redshift for
our sample for first peak, Pλ1
42- 46 F5.3 --- Pl2 Probability of obtaining a particular richness
λMCMF as a function of redshift for
our sample for second peak, Pλ2
48- 52 F5.3 --- Ps1 Fraction of sources in the random catalogue
with |zRASS-zrand|<0.075 that have a
signal-to-noise ratio S equal to or below
that found for the RASS cluster candidate
for first peak, Ps1
54- 58 F5.3 --- Ps2 Fraction of sources in the random catalogue
with |zRASS-zrand|<0.075 that have a
signal-to-noise ratio S equal to or below
that found for the RASS cluster candidate
for first peak, Ps2
60- 64 F5.3 --- P* Probability of a source being an
X-ray-emitting UCAC4 source
65- 69 F5.3 --- z1 Photometric redshift of first peak
71- 75 F5.3 --- z2 ?=- Photometric redshift of second peak
77- 81 F5.3 --- e_z1 rms uncertainty on z1, σz,1
83- 87 F5.3 --- e_z2 ?=- rms uncertainty on z2, σz,2
89- 93 F5.1 --- lMCMF1 Richness for first peak, λMCMF1
95- 98 F4.1 --- lMCMF2 ?=- Richness for second peak, λMCMF2
100-103 F4.1 --- e_lMCMF1 rms uncertainty on lMCMF1, σλ1
105-108 F4.1 --- e_lMCMF2 ?=- rms uncertainty on lMCMF2,
σλ2
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 26-Feb-2021