J/ApJS/276/21 Finding galaxy clusters with machine learning (Tian+, 2025)
COSMIC: a galaxy cluster-finding algorithm using machine learning.
Tian D.-C., Yang Y., Wen Z.-L., Xia J.-Q.
<Astrophys. J. Suppl. Ser., 276, 21 (2025)>
=2025ApJS..276...21T 2025ApJS..276...21T
ADC_Keywords: Clusters, galaxy; Redshifts; Photometry, SDSS; Optical
Keywords: Galaxy clusters ; Brightest cluster galaxies ; Classification ;
Convolutional neural networks
Abstract:
Building a comprehensive catalog of galaxy clusters is a fundamental
task for studies on structure formation and galaxy evolution. In this
paper, we present Cluster Optical Search using Machine Intelligence in
Catalogs (COSMIC), an algorithm utilizing machine learning techniques
to efficiently detect galaxy clusters. COSMIC involves two steps, the
identification of the brightest cluster galaxies and the estimation of
cluster richness. We train our models on galaxy data from the Sloan
Digital Sky Survey and the WHL galaxy cluster catalog. Validated
against test data in the region of the northern Galactic cap, the
COSMIC algorithm demonstrates high completeness when crossmatching
with previous cluster catalogs. Richness comparison with previous
optical and X-ray measurements also demonstrates a tight correlation.
Our methodology showcases robust performance in galaxy cluster
detection and holds promising prospects for applications in upcoming
large-scale surveys. The COSMIC codes are published on
https://github.com/tdccccc/COSMIC.
Description:
We use the data of galaxies and galaxy clusters in SDSS to develop the
Cluster Optical Search using Machine Intelligence in Catalogs (COSMIC)
algorithm.
COSMIC is applied to the photometric data from SDSS. Within a test sky
region of ∼200deg2, we detect 3653 galaxy clusters. Our cluster
catalog contains most of the rich clusters in previous SDSS cluster
catalogs, and the X-ray clusters in the eROSITA X-ray cluster catalog.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 125 3653 Clusters of galaxies identified from the test data
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
III/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)
J/ApJ/660/239 : MaxBCG cat. of galaxy clusters from SDSS (Koester+, 2007)
J/ApJS/183/197 : Galaxy clusters identified from the SDSS-DR6 (Wen+, 2009)
J/ApJS/191/254 : GMBCG galaxy cluster catalog from SDSS DR7 (Hao+, 2010)
J/ApJ/736/21 : Galaxy clusters opt. cat. from AMF on SDSS DR6 (Szabo+ 2011)
J/ApJS/199/34 : Clusters of galaxies in SDSS-III (Wen+, 2012)
J/MNRAS/436/275 : Relaxation param. of 2092 rich galaxy clusters (Wen+, 2013)
J/MNRAS/444/147 : Richness of galaxy clusters (Oguri, 2014)
J/ApJS/216/27 : Galaxy clusters with the SPT-SZ survey (Bleem+, 2015)
J/ApJ/807/178 : Rich galaxy clusters identified in SDSS-DR12 (Wen+, 2015)
J/ApJS/224/1 : redMaPPer cluster catalog from DES data (Rykoff+, 2016)
J/MNRAS/481/4158 : 1959 massive galaxy clusters at high redshifts (Wen+, 2018)
J/ApJS/253/3 : Sunyaev-Zel'dovich galaxy clusters with ACT (Hilton+, 2021)
J/ApJS/253/56 : Galaxy clusters from the DESI surveys. I. (Zou+, 2021)
J/A+A/668/A99 : Gaia DR3 quasar and galaxy classification (Hughes+, 2022)
J/MNRAS/513/3946 : Clusters of galaxies from DES*unWISE data (Wen+, 2022)
J/MNRAS/526/3757 : RASS-MCMF catalog (Klein+, 2023)
J/A+A/685/A106 : eRASS. Galaxy clusters and groups in WGH (Bulbul+, 2024)
J/A+A/688/A210 : eRASS. Opt. properties of clusters and groups (Kluge+, 2024)
J/A+A/688/A187 : MCXC Second release (MCXC-II) (Sadibekova+, 2024)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [0/3652] Sequential Cluster ID
6- 15 F10.6 deg RAdeg [150/160] Right Ascension, of BCG (J2000)
17- 25 F9.6 deg DEdeg [6e-05/20] Declination, of BCG (J2000)
27- 34 F8.6 --- zcl [0.03/0.75] Cluster redshift
36- 44 F9.6 mag rBCGmag [13.34/21.31] r-band AB magnitude of the
brightest cluster galaxy (BCG)
46- 55 F10.6 --- R [10/130] Cluster Richness
57- 64 F8.6 Mpc r500 [0.44/1.3] Cluster Radius
66- 73 F8.6 10+14Msun M500 [0.46/9] Derived cluster mass
75- 76 I2 --- Ngal [6/94] Number, member galaxies within r500
78-125 A48 --- Other Reference notes for previously known
clusters (1)
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Note (1): Reference notes for previously known clusters as follows:
CluMPR = Yantovski-Barth et al. (2024MNRAS.531.2285Y 2024MNRAS.531.2285Y)
GMBCG = Hao et al. (2010, J/ApJS/191/254;
in Simbad)
MaxBCG = Koester et al. (2007, J/ApJ/660/239)
WHL = Wen & Han (2015, J/ApJ/807/178;
<[WHL2012] JHHMMSS.s+DDMMSS> in Simbad)
Yang+21 = Yang et al. (2021ApJ...909..143Y 2021ApJ...909..143Y)
Zou+21 = Zou et al. (2021, J/ApJS/253/56)
redMaPPer = Rykoff et al. (2016, J/ApJS/224/1;
<[RRB2014] RM JHHMMSS.s+DDMMSS.s> in Simbad)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 27-Oct-2025