J/A+A/697/A197 COSMOS-Web deep galaxy group catalog up to z=3.7 (Toni+, 2025)
The COSMOS-Web deep galaxy group catalog up to z=3.7.
Toni G., Gozaliasl G., Maturi M., Moscardini L., Finoguenov A.,
Castignani G., Gentile F., Virolainen K., Casey C.M., Kartaltepe J.S.,
Akins H.B., Allen N., Arango-Toro R.C., Babul A., Brinch M., Drakos N.E.,
Faisst A.L., Franco M., Griffiths R.E., Harish S., Hasinger G., Ilbert O.,
Jin S., Khostovan A.A., Koekemoer A.M., Korpi-Lagg M., Larson R.L.,
Lertprasertpong J., Liu D., Magdis G., Massey R., McCracken H.J.,
McKinney J., Paquereau L., Rhodes J., Robertson B.E., Sargent M.,
Shuntov M., Tanaka M., Taamoli S., Tempel E., Toft S., Vardoulaki E.,
Yang L.
<Astron. Astrophys. 697, A197 (2025)>
=2025A&A...697A.197T 2025A&A...697A.197T (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts ; Infrared sources
Keywords: galaxies: clusters: general - galaxies: evolution -
galaxies: groups: general - galaxies: high-redshift -
galaxies: luminosity function, mass function -
large-scale structure of Universe
Abstract:
Galaxy groups with total masses below ∼1014M☉ and up to a few
tens of members are the most common galaxy environment, marking the
transition between the field and the most massive galaxy clusters. In
this framework, identifying and studying groups plays a crucial role
in understanding structure formation and galaxy evolution. Despite the
challenges in detecting such relatively small structures, modern deep
surveys allow us to build well-characterized samples of galaxy groups
up to the regime where the structures we observe today were taking
shape. We aim to build the largest deep catalog of galaxy groups to
date over the COSMOS-Web field effective area of 0.45deg2. We
leveraged the deep imaging, high resolution, and high-quality
photometry from the James Webb Space Telescope observations of the
COSMOS-Web field. We used the recent COSMOS-Web photometric catalog
with sky position, photometric redshift, and magnitude in a reference
band for each selected galaxy. We performed the group search with the
Adaptive Matched Identifier of Clustered Objects (AMICO) algorithm, a
linear matched filter based on an analytical model for the
cluster/group signal. This algorithm has already been tested in wide
and deep field surveys, including a successful application to COSMOS
data up to z=2. In this work, we tested the algorithm's performances
at even higher redshift and searched for protocluster cores and groups
at z>2. To benchmark this relatively unexplored regime, we compiled a
list of known protoclusters in COSMOS at 2≤z≤3.7 and matched them
with our detections. We studied the spatial connection between
detected cores through a clustering analysis. We estimated the purity
and the completeness of our group sample by creating data-driven mocks
via a Monte Carlo approach with the SinFoniA code and linked
signal-to-noise to purity levels to define desired purity thresholds.
We detected 1678 groups in the COSMOS-Web field up to z=3.7 with a
purity level of ∼77%, providing a deep catalog of galaxy members that
extends nearly two magnitudes deeper than the previous application of
AMICO to COSMOS. Around 670 groups have been detected with a purity of
90%. Our catalog includes more than 850 groups whose photometric
redshift was confirmed by assigning robust spectroscopic counterparts.
This catalog of galaxy groups is the largest ultra-deep group sample
built on JWST observations so far and offers a unique opportunity to
explore several aspects of galaxy evolution in different environments
spanning ∼12Gyr and study groups themselves, from the least rich
population of groups to the formation of the most massive clusters.
Description:
We present the COSMOS-Web deep galaxy group catalog obtained by
applying the AMICO algorithm to the COSMOS-Web photometric galaxy
catalog, the result of the largest contiguous JWST observation to
date. The catalog contains 1678 candidate groups and protocluster
cores up to z=3.7. The group catalog is accompanied by the list of
associated members.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
groups.dat 129 1678 Catalog of candidate group detections
membship.dat 37 1745652 Galaxy memberships with probability>0.005
--------------------------------------------------------------------------------
See also:
J/ApJ/837/16 : Cosmic web of galaxies in the COSMOS field (Darvish+, 2017)
J/ApJ/874/53 : COSMOS galaxies with ALMA 345.7GHz + 342.3GHz obs.
(Betti+, 2019)
J/ApJS/263/27 : CLAMATO DR2 redshift catalog (Horowitz+, 2022)
J/A+A/685/A25 : Faint, unobscured quasars at z>6 (Andika+, 2024)
Byte-by-byte Description of file: groups.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID [1/1816] Group identification number
6- 14 F9.5 deg RAdeg Right Ascension (J2000)
16- 24 F9.7 deg DEdeg Declination (J2000)
26- 29 F4.2 --- z AMICO group redshift
31- 39 F9.7 --- S/N Signal-to-noise ratio,
including background and group contributions
41- 50 F10.7 --- S/Nnocl Signal-to-noise ratio,
including only background
52- 61 F10.8 --- Amp Signal amplitude
63- 73 F11.9 --- MskFrc Fraction of the group inaccessible because
of mask
75- 84 F10.6 --- lambda Apparent richness based on the galaxy
probability association
(visible number of galaxies)
86- 95 F10.7 --- lambda* Intrinsic richness (as lambda but M<Mstar+1.5,
r<R200 of a group with mass 1014M☉/h)
97- 99 I3 --- DetFlag Detection flag (see Sect. 4.3) (1)
101-103 I3 --- Nspec ?=-99 Number of members with spectroscopic
redshift
105-116 F12.10 --- e_z 1-sigma lower uncertainty on redshift
118-129 E12.10 -- E_z 1-sigma upper uncertainty on redshift
--------------------------------------------------------------------------------
Note (1): Our flagging system is based on a list of base-2 flag bits referring
to the following properties, ordered starting from the less severe:
1 = lack of spectroscopic members
2 = less than 3 arcmin from a border edge
4 = X-ray projection or proximity flag 1
8 = masked fraction larger than 25%
16 = central X-ray selected AGN (obtained via matching with the
X-ray sources in COSMOS-Web or COSMOS2020)
32 = spectroscopic mismatch (see Sect. 4.2)
64 = low intrinsic richness (lambda*<5)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: membship.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- GalaxyID COSMOS-Web galaxy identification number
(Shuntov et al. in prep.)
8- 19 E12.10 --- FieldProb Probability to belong to the field
21- 24 I4 --- ID [1/1816] Group identification number
26- 37 F12.10 --- AssocProb Probability to belong to the group
indicated in ID
--------------------------------------------------------------------------------
Acknowledgements:
Greta Toni, greta.toni4(at)unibo.it
(End) Patricia Vannier [CDS] 15-Apr-2025