J/ApJ/742/125 Galaxies in X-ray groups. I. COSMOS memberships (George+, 2011)
Galaxies in X-ray groups.
I. Robust membership assignment and the impact of group environments on
quenching.
George M.R., Leauthaud A., Bundy K., Finoguenov A., Tinker J., Lin Y.-T.,
Mei S., Kneib J.-P., Aussel H., Behroozi P.S., Busha M.T., Capak P.,
Coccato L., Covone G., Faure C., Fiorenza S.L., Ilbert O., Le Floc'h E.,
Koekemoer A.M., Tanaka M., Wechsler R.H., Wolk M.
<Astrophys. J., 742, 125 (2011)>
=2011ApJ...742..125G 2011ApJ...742..125G
ADC_Keywords: Galaxy catalogs; X-ray sources; Spectra, optical; Redshifts
Keywords: catalogs ; galaxies: groups: general ; galaxies: star formation
Abstract:
Understanding the mechanisms that lead dense environments to host
galaxies with redder colors, more spheroidal morphologies, and lower
star formation rates than field populations remains an important
problem. As most candidate processes ultimately depend on host halo
mass, accurate characterizations of the local environment, ideally
tied to halo mass estimates and spanning a range in halo mass and
redshift, are needed. In this work, we present and test a rigorous,
probabilistic method for assigning galaxies to groups based on precise
photometric redshifts and X-ray-selected groups drawn from the COSMOS
field. The groups have masses in the range
1013≲M200c/M☉≲1014 and span redshifts 0<z<1. We
characterize our selection algorithm via tests on spectroscopic
subsamples, including new data obtained at the Very Large Telescope,
and by applying our method to detailed mock catalogs. We find that our
group member galaxy sample has a purity of 84% and completeness of 92%
within 0.5R200c. We measure the impact of uncertainties in redshifts
and group centering on the quality of the member selection with
simulations based on current data as well as future imaging and
spectroscopic surveys. As a first application of our new group member
catalog which will be made publicly available, we show that member
galaxies exhibit a higher quenched fraction compared to the field at
fixed stellar mass out to z∼1, indicating a significant relationship
between star formation and environment at group scales. We also
address the suggestion that dusty star-forming galaxies in such groups
may impact the high-l power spectrum of the cosmic microwave
background and find that such a population cannot explain the low
power seen in recent Sunyaev-Zel'dovich measurements.
Description:
The COSMOS field has been observed in a broad range of wavelengths,
with imaging data from X-ray to radio and number of spectroscopic
campaigns.
We have added to the spectroscopic sample in groups with a recent
campaign using the Focal Reducer and low dispersion Spectrograph 2
(FORS2) at the VLT (Program ID 084.B-0523; PI: Mei). Data were taken
on four clear nights with excellent conditions and 0.8" typical
seeing from 2010 February 14-18.
X-ray imaging has been taken with the XMM-Newton (1.5Ms covering
2.13deg2; Hasinger+ 2007, J/ApJS/172/29 and Cappelluti+ 2009,
J/A+A/497/635) and Chandra observatories (1.8Ms covering 0.9deg2;
Elvis+ 2009, J/ApJS/184/158).
The entire COSMOS region has been mapped through 54 overlapping
XMM-Newton pointings and additional Chandra observations covering the
central region (0.9deg2) with higher spatial resolution. A mosaic
combining these two data sets has been used to find and measure the
fluxes of groups using a wavelet transform method described in
Vikhlinin+ (1998, J/ApJ/502/558).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
xgroups.dat 433 183 COSMOS X-ray group membership catalog
xgal.dat 253 115844 COSMOS galaxy membership catalog
--------------------------------------------------------------------------------
Description of files:
README_galaxies.txt and README_groups.txt are the ReadMe files provided
by the authors containing an FAQ section.
See also:
II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
VII/265 : COSMOS Morphological Catalog (V1.1) (Tasca+ 2009)
J/ApJ/502/558 : Catalog of ROSAT galaxy clusters (Vikhlinin+ 1998)
J/ApJ/496/39 : Properties of poor groups of galaxies. I. (Zabludoff+ 1998)
J/ApJ/549/172 : X-ray-detected, poor groups galaxy populations (Tran+, 2001)
J/MNRAS/348/866 : 2dFGRS Percolation-Inferred Gal. Group (2PIGG) (Eke+, 2004)
J/ApJ/625/6 : Gal. groups in DEEP2 Galaxy Redshift Survey (Gerke+, 2005)
J/ApJS/157/1 : Red-Sequence Cluster Survey (Gladders+, 2005)
J/AJ/130/968 : SDSS-C4 cluster catalog (Miller+, 2005)
J/ApJS/167/1 : Galaxy groups and clusters from SDSS (Berlind+, 2006)
J/ApJ/644/100 : SDSS quasars in the COSMOS field (Prescott+, 2006)
J/ApJS/172/182 : XMM Clusters of galaxies in COSMOS field (Finoguenov+ 2007)
J/ApJS/172/29 : XMM-Newton survey in COSMOS field. I. (Hasinger+, 2007)
J/ApJS/172/70 : zCOSMOS-bright catalog (Lilly+, 2007)
J/ApJS/172/368 : XMM-Newton survey in COSMOS field. IV. (Mainieri+, 2007)
J/A+A/461/81 : Galaxy clusters in the CFHTLS (Olsen+, 2007)
J/A+A/497/635 : XMM-Newton wide-field survey in COSMOS (Cappelluti+, 2009)
J/ApJS/184/158 : Chandra COSMOS survey I. (Elvis+, 2009)
J/A+A/494/845 : Galaxy clusters in the CFHTLS (Grove+, 2009)
J/ApJ/690/1236 : COSMOS photometric redshift catalog (Ilbert+, 2009)
J/ApJ/697/1842 : zCOSMOS 10K sample group catalog to z=1 (Knobel+, 2009)
J/MNRAS/403/2063 : SXDF X-ray groups and galaxy clusters (Finoguenov+, 2010)
J/MNRAS/413/1145 : Galaxy clusters in the COSMOS field (Bellagamba+, 2011)
J/ApJ/753/121 : zCOSMOS 20k sample group catalog to z≲1.2 (Knobel+, 2012)
J/ApJ/790/16 : X-ray ETGs in the Chandra COSMOS survey (Civano+, 2014)
J/ApJ/865/43 : X-ray analysis of Chandra-COSMOS gal. (Fornasini+, 2018)
http://irsa.ipac.caltech.edu/data/COSMOS/ : COSMOS home page on NASA/IPAC IRSA
Byte-by-byte Description of file: xgroups.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- GID [11/345] Group ID number
(<[GLB2011] Group NNN> in Simbad)
(GROUP_ID)
5- 27 E23.18 deg RAdeg [149.4/151] X-ray right ascension (J2000)
(RA)
29- 51 E23.18 deg DEdeg [1.5/3] X-ray declination (J2000) (DEC)
53- 67 E15.10 deg ePos [0.00014/0.009] Position uncertainty
of X-ray source (XRAYPOSERR)
69- 83 E15.10 --- z [0.078/1] Group redshift (REDSHIFT) (1)
85- 99 E15.10 --- e_z [0.00013/0.014] z uncertainty (REDSHIFT_ERR)
101- 115 E15.10 [10-7W] logLx [41.3/44.1] Log of X-ray luminosity
in the rest-frame 0.1-2.4keV band;
in erg/s units (LX)
117- 131 E15.10 [10-7W] e_logLx [40.7/42.9] logLx uncertainty (LX_ERR)
133- 147 E15.10 --- LxScale [41.3/43.9] log of scaled X-ray luminosity
(Lx/E(z)) (LX_SCALE)
149- 164 E16.10 [mW/m2] Fx [-15.5/-12.7] log of extrapolated 0.5-2kev
flux within R500 in ergs/s/cm2
(XRAY_FLUX)
166- 181 E16.10 [mW/m2] e_Fx [-15.7/-14.3] Fx uncertainty (XRAYFLUXERR)
183 I1 --- Mask [0/1] Mask flag (1=masked, 0=clean)
(FLAG_MASK)
185 I1 --- Poor [0/1] Poor group flag (1=three or fewer
members, 0=4+ members) (FLAG_POOR)
187 I1 --- Merger [0/4] Merger flag (N=number of
overlapping groups) (FLAG_MERGER)
189 I1 --- Qual [0/1] Combined quality flag (1=good
(129 occurrences) or 0=bad) (FLAG_INCLUDE)
191- 205 E15.10 [Msun] logM200c [12.8/14.4] log Mass M200c (M200C)
207- 221 E15.10 Mpc R200c [0.36/1.1] Physical radius R200c
(R200C_MPC)
223- 237 E15.10 arcsec AR200c [53/347.1] Angular radius at group redshift
(R200C_AS)
239- 253 E15.10 --- Conc200c [3.5/5.4] Concentration c200c
(C=R200/Rscale)
255- 257 I3 --- Nmm [0/219] Number of group members (P_MEM>0.5)
(NMEM)
259- 273 E15.10 --- Pmm [0/166.418] Sum of P_MEM over all galaxies
(NMEM_W)
275- 298 E24.18 deg RAMdeg [149.4/151]?=-999 Right ascension of Most
Massive Group Galaxy within NFW scale
radius (J2000) (RA_MMGGS)
300- 323 E24.18 deg DEMdeg [1.6/3]?=-999 Declination of Most Massive
Group Galaxy within NFW scale radius
(J2000) (DEC_MMGGS)
325- 330 I6 --- MMGGS [1050/200932]?=-1 ID number of Most Massive
Group Galaxy within Navarro-Frenk-White
(NFW) scale radius (MMGGS) (ID_MMGGS)
332- 347 E16.10 [Msun] logMM [9/12]?=-1 Log of stellar mass of MMGGS
(SM_MMGGS)
349- 372 E24.18 deg RAZdeg [149.4/151]?=-999 RA_MMGGS using
spectroscopic redshift (RAMMGGSZBEST)
374- 397 E24.18 deg DEZdeg [1.6/3]?=-999 DEC_MMGGS using
spectroscopic redshift (DECMMGGSZBEST)
399- 404 I6 --- IDzM [1050/200991]?=-1 ID_MMGGS using
spectroscopic redshift (IDMMGGSZBEST)
406- 431 A26 --- [GLB2011] COSMOS CL JHHMMSS.s+DDMMSS name (NAME)
433 I1 --- xFlag [1/3] X-ray quality flag (2)
--------------------------------------------------------------------------------
Note (1): Group redshifts have been determined by searching for red sequence
overdensities within 500kpc of the X-ray centers and are refined by
using spectroscopic redshifts when available. We use groups with z<1
to ensure good optical identifications and small photoz uncertainties.
Note (2): A quality flag is assigned to the reliability of the optical
counterpart, with flags 1 and 2 indicating a secure association (165 groups),
and higher flags indicating potential problems due to projections with
other sources or bad photometry due to bright stars in the foreground.
Code as follows:
1 = can use X-ray center, all good
2 = good ID, but cannot use X-ray center
3 = ID needs to be checked spectroscopically
--------------------------------------------------------------------------------
Byte-by-byte Description of file: xgal.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 I7 --- ID [2/1443962] Galaxy ID number
(<[GLB2011] Galaxy NNNNNNN> in Simbad)
(GAL_ID)
9- 23 E15.10 mag F814mag [15/24.2] HST/ACS F814W SExtractor AB
magnitude (Leauthaud+, 2007ApJS..172..219L 2007ApJS..172..219L)
(MAG_AUTO)
25- 47 E23.18 deg RAdeg [149.4/150.8] Right ascension (J2000) (RA)
49- 71 E23.18 deg DEdeg [1.5/2.9] Declination (J2000) (DEC)
73- 87 E15.10 [Msun] logM [5.1/12.1] Log of stellar mass (SM)
89- 103 E15.10 [Msun] e_logM [4.7e-7/0.4] LogM uncertainty (EM_ERR)
105- 120 E16.10 --- zphot [0.001/4.7]?=-99 Photometric redshift
from Ilbert+, 2009, J/ApJ/690/1236
122- 137 E16.10 --- e_zphot [0.0015/4.7]?=-99 Lower uncertainty on zphot
(ZPHOT_ERRLO)
139- 154 E16.10 --- E_zphot [0.008/5]?=-99 Upper uncertainty on zphot
(ZPHOT_ERRHI)
156 I1 --- MMGGS [0/1] Most Massive Group Galaxy within
Navarro-Frenk-White (NFW) scale radius
(Rs=R200c/c200c)
158- 172 E15.10 --- Pmm [0/1] Membership probability (P_MEM)
174- 176 I3 --- GID [11/345]?=-1 Group ID number of most likely
group (GROUP_ID)
178 I1 --- f_GID [0/1] Group flag (1=good, 0=bad) (GROUP_FLAG)
180- 195 E16.10 pc Dist [0/1]?=-1 Projected distance to MMGGS
of Group ID (R/R200) (DIST_MMGGS)
197 I1 --- MMGGz [0/1] MMGGS using GAL_ID's
spectroscopic redshift (MMGGS_ZBEST)
199- 213 E15.10 --- PMMGGz [0/1] Membership probability using
GAL_ID's spectroscopic redshift (PMEMZBEST)
215- 217 I3 --- GIDz [11/345]?=-1 GROUP_ID using GAL_ID's
spectroscopic redshift (GROUPIDZBEST)
219 I1 --- f_GIDz [0/1] Group flag using GAL_ID's
spectroscopic redshift (GROUPFLAGZBEST)
221- 236 E16.10 --- Distz [0/1]?=-1 DIST_MMGGS using GAL_ID's
spectroscopic redshift (R/R200)
(DISTMMGGSZBEST)
238- 253 E16.10 mag NUV-R [-0.85/6.4] NUV-R color index (MNUV_MR)
--------------------------------------------------------------------------------
History:
Downloaded from http://irsa.ipac.caltech.edu/data/COSMOS/tables/groups/
References:
George et al. Paper II. 2012ApJ...757....2G 2012ApJ...757....2G
George et al. Paper III. 2013ApJ...770..113G 2013ApJ...770..113G
(End) Emmanuelle Perret [CDS] 20-Jan-2021