J/ApJS/278/51 Spectroscopic redshift survey of the Coma cluster (Kang+, 2025)
A redshift survey of the Coma Cluster (A1656): understanding the nature of
subhalos in the weak-lensing map.
Kang W., Hwang Ho S., Okabe N., Park C.
<Astrophys. J. Suppl. Ser., 278, 51 (2025)>
=2025ApJS..278...51K 2025ApJS..278...51K
ADC_Keywords: Clusters, galaxy; Spectra, optical; Redshifts; Surveys;
Gravitational lensing; Magnitudes
Keywords: Galaxy clusters ; Coma Cluster ; Redshift surveys ;
Weak gravitational lensing ; Dark matter
Abstract:
We study the physical properties of weak-lensing subhalos in the Coma
cluster of galaxies using data from galaxy redshift surveys. The data
include 12,989 galaxies with measured spectroscopic redshifts
(2184 from our MMT/Hectospec observations and 10,807 from the
literature). The r-band magnitude limit at which the differential
spectroscopic completeness drops below 50% is 20.2mag, which is
spatially uniform in a region of 4.5deg2 where the weak-lensing map of
Okabe+ 2014ApJ...784...90O 2014ApJ...784...90O exists. We identify 1337 member galaxies in
this field and use them to understand the nature of 32 subhalos
detected in a weak-lensing analysis. We use Gaussian mixture modeling
(GMM) in the line-of-sight velocity domain to measure the mean
velocity, the velocity dispersion, and the number of subhalo galaxies
by mitigating contamination from interloping galaxies. Using subhalo
properties calculated with the GMM, we find no significant difference
in the redshift space distribution between the cluster member galaxies
and subhalos. We find that the weak-lensing mass shows strong
correlations with the number of subhalo member galaxies, velocity
dispersion, and dynamical mass of subhalos with power-law slopes of
0.54-0.15+0.16, 0.93-0.32+0.35, and 0.50_-0.18+0.31,
respectively. The slope of the mass-velocity dispersion relation of
the weak-lensing subhalos appears shallower than that of galaxy
clusters, galaxy groups, and individual galaxies. These results
suggest that the combination of redshift surveys with weak-lensing
maps can be a powerful tool for better understanding the nature of
subhalos in clusters.
Description:
We use the Sloan Digital Sky Survey (SDSS) Data Release 17 (DR17;
Abdurro'uf+ 2022, III/286) photometric catalog as the basis for
compiling our redshift catalog.
We conducted spectroscopic observations using the 6.5m MMT telescope
with Hectospec to obtain redshifts of galaxies in the field of the
Coma cluster. These observations are part of the KIAS redshift survey
of nearby galaxy clusters. Hectospec is a 300 fiber multiobject
spectrograph which provides a spectral resolution of R∼1000-2000 in
the wavelength range 3650-9500Å. With these instruments, we
observed 12 fields for 11 nights between 2014-Apr-02 and 2019-Apr-28
and obtained 3048 spectra of galaxies.
To fully analyze the 4.5deg2 region covered by the weak-lensing
analysis of Okabe+ (2014ApJ...784...90O 2014ApJ...784...90O) shown in the left panel of
Figure 1, we also compile spectroscopic redshifts of galaxies
available in the literature. Within the weak-lensing field, we
retrieve 2257 galaxy redshifts from SDSS DR17 and 73 from the
NASA/IPAC Extragalactic Database (NED). In addition, the Early Data
Release (EDR) of the Dark Energy Spectroscopic Instrument (DESI; DESI
Coll. 2024AJ....168...58D 2024AJ....168...58D) became available in 2023.
We include 8477 redshifts from DESI EDR for galaxies in the
weak-lensing map region without previously measured redshifts in this
field. The total number of galaxies with measured redshifts is
12990 in the 4.5deg2 field.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
12 59 44.40 +27 54 44.8 NAME Coma Cluster = ACO 1656
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 79 37758 Redshift catalog of objects within 132' of the Coma
cluster center
refs.dat 59 44 References
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See also:
VII/86 : Groups of Galaxies. I. Nearby Groups (Huchra+ 1982)
VII/158 : Revised and Updated Catalog of Quasi-stellar Objects (Hewitt+ 1993)
VII/200 : Minislice at the North Galactic Pole. II. (Willmer+ 1996)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
III/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)
VII/292 : DESI Legacy Imaging Surveys DR8 photometric redshifts (Duncan, 2022)
V/161 : DESI DR1 redshift catalog (DESI Col.+ 2025)
II/388 : Euclid final merged catalog. Q1 data release (Euclid Coll., 2025)
J/ApJS/109/45 : Kitt Peak galaxy redshift survey (Munn+ 1997)
J/MNRAS/300/303 : UV-selected galaxy redshift survey (Treyer+, 1998)
J/MNRAS/312/442 : UV-selected galaxy redshift survey. II. (Sullivan+, 2000)
J/AJ/121/2331 : SDSS redshifts in the Coma cluster (Castander+, 2001)
J/AJ/121/66 : KISS Hα survey list 1 (Salzer+, 2001)
J/AJ/130/496 : KISS emission-line galaxy candidates (Jangren+, 2005)
J/A+A/469/1211 : XMM-Newton survey of SA 57 (Trevese+, 2007)
J/ApJS/191/254 : GMBCG galaxy cluster catalog from SDSS DR7 (Hao+, 2010)
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
J/AJ/142/148 : IR obs. of galaxies in the Coma cluster (Edwards+, 2011)
J/A+A/544/A81 : Supernovae and their hosts in the SDSS DR8 (Hakobyan+, 2012)
J/ApJ/767/15 : Hectospec Cluster Survey (HeCS) (Rines+, 2013)
J/A+A/558/A75 : 2XMMi/SDSS Galaxy Cluster Survey. II. (Takey+, 2013)
J/ApJ/783/52 : Redshifts in the field of A383 (Geller+, 2014)
J/ApJS/213/35 : SHELS: galaxy redshift survey for R≤20.6 (Geller+, 2014)
J/ApJ/797/106 : Redshifts in nine galaxy cluster fields (Hwang+, 2014)
J/ApJ/792/45 : SPT-SZ survey galaxy clusters optical sp. (Ruel+, 2014)
J/ApJ/785/104 : redMaPPer. I. Algorithm applied to SDSS DR8 (Rykoff+, 2014)
J/ApJS/217/27 : Morphologies of z<0.01 SDSS-DR7 galaxies (Ann+, 2015)
J/ApJ/807/178 : Rich galaxy clusters identified in SDSS-DR12 (Wen+, 2015)
J/ApJS/224/11 : SHELS: redshift survey of the F1 DLS field (Geller+, 2016)
J/ApJ/819/63 : Hectospec survey of SZ clusters (HeCS-SZ) (Rines+, 2016)
J/ApJ/836/99 : NuSTAR serendipitous survey: 40-month cat. (Lansbury+, 2017)
J/MNRAS/468/3322 : CoMaLit. V. Mass forecasting with proxies (Sereno+, 2017)
J/ApJS/229/20 : MMT/Hectospec redshift survey for Abell 2029 (Sohn+, 2017)
J/ApJ/861/49 : ALFALFA extragalactic HI source catalog (Haynes+, 2018)
J/ApJ/863/102 : Spectroscopic redshift catalog in A2142 field (Liu+, 2018)
J/ApJS/240/6 : LAMOST Quasar Survey: Data Releases 4 and 5 (Yao+, 2019)
J/ApJ/891/129 : The HeCS-omnibus catalog: SDSS & MMT sp. obs. (Sohn+, 2020)
J/A+A/650/A76 : HI content in Coma cluster substructure (Healy+, 2021)
J/ApJS/267/16 : Strong [OIII]5007 emission-line compact gal. (Liu+, 2023)
J/ApJS/267/27 : SMUDGes V. Complete cat. of UDGs from DR9 (Zaritsky+, 2023)
J/ApJS/272/22 : Gal. with redshifts in the vicinity of A426 (Kang+, 2024)
J/A+A/694/A216 : Catalog of Coma cluster members (Jimenez-Teja+, 2025)
http://www.sdss.org/ : SDSS homepage
http://www.desi.lbl.gov/ : DESI homepage
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Seq [1/37758] Sequence number
7- 25 I19 --- ObjID ObjID in SDSS catalog
27- 36 F10.6 deg RAdeg [192.5/197.5] Right ascension (J2000)
38- 46 F9.6 deg DEdeg [25.8/30.2] Declination (J2000)
48- 53 F6.3 mag rmag [11.68/23.15] Apparent extinction corrected
r-band Petrosian magnitude
55 I1 --- PS [0/1]? Flag for point source (1)
57- 65 F9.6 --- z [-0.0041/5.64] Redshift
67- 74 F8.6 --- e_z [0/3.5] Uncertainty in z
76- 77 I2 --- r_z [1/44] Reference for z (1=this work
(2194 occurrences); see refs.dat file)
79 I1 --- Mm [0/1]? Flag for cluster membership; Section 2.3 (2)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
1 = point source (10863 occurrences)
0 = extended source (26895 occurrences)
Note (2): Flag as follows:
1 = member of Coma cluster (1826 occurrences)
0 = non-member (35932 occurrences)
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference code
4- 22 A19 --- Auth First author's name(s)
24-42 A19 --- BibCode Bibcode of the reference
45-59 A15 --- Comm Comment
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Feb-2026