COSMOS X-ray Group Member Galaxy Catalog Definitions


The reference for this catalog is George et al. (2011). This is a group membership catalog drawn from the COSMOS ACS galaxy catalog, similar to the one presented in Leauthaud et al. (2007). The main difference between this catalog and the Leauthaud et al 2007 one is that the raw ACS images have now been corrected for the effects of charge transfer inefficiency (CTI, see Massey et al. 2010 for further details). Since the CTI correction scheme slightly changes the noise properties of the raw images, the detections have also changed. For this reason, the GAL_ID field in this catalog can not be used to match to objects in the 2007 catalog. The pixel scale for this catalog is 0.03". To reference this ACS catalog please reference Leauthaud 2007 with updates presented in Leauthaud et al (in prep). This catalog is truncated at F814W (MAG_AUTO) < 24.2 due to the K-band completeness limit for stellar masses and because photoz uncertainties rise near this limit. Objects within ACS masks have also been removed (these are the same masks as in Leauthaud et al. 2007) and a variety of bad detections have been removed ("clean"=1 and "mu_class"=1) as well as galaxies without stellar masses.

The galaxy catalog contains ACS photometric parameters, stellar masses, photoz information, and group membership associations. Please see the README for more details.

Name Intype Units Description
GAL_ID long Galaxy ID number
MAG_AUTO float mag F814W SExtractor magnitude from Leauthaud et al. (2007)
ra double deg Right Ascension (J2000) from Leauthaud et al. (2007)
dec double deg Declination (J2000) from Leauthaud et al. (2007)
SM float log(M / Msun) Stellar mass estimate
SM_ERR float log(M / Msun) Uncertainty of SM
Error is from model fit and does not include photo-z, photometric, or IMF uncertainties.
ZPHOT float Photometric redshift from Ilbert et al. (2009).
ZPHOT_ERRLO float ZPHOT lower error bar from Ilbert et al. (2009).
ZPHOT_ERRHI float ZPHOT upper error bar from Ilbert et al. (2009).
MMGGS int Most Massive Group Galaxy within NFW scale radius
P_MEM float Membership probability
GROUP_ID int Group ID number of most likely group
GROUP_FLAG int Group flag (1=good, 0=bad)
DIST_MMGGS float R/R200 Projected distance to MMGGS of GROUP_ID in units of R200
MMGGS_ZBEST int MMGGS using GAL_ID's spectroscopic redshift
P_MEM_ZBEST float P_MEM using GAL_ID's spectroscopic redshift
GROUP_ID_ZBEST int GROUP_ID using GAL_ID's spectroscopic redshift
GROUP_FLAG_ZBEST int GROUP_FLAG using GAL_ID's spectroscopic redshift
DIST_MMGGS_ZBEST float R/R200 DIST_MMGGS using GAL_ID's spectroscopic redshift
MNUV_MR float mag NUV-R color from Ilbert et al. (2009).