Gfinder Halo-based Group Catalog

Description

This VAC is the updated version of extended halo-based group catalog based on DESI Legecy Imaging Surveys DR9. The spectroscopic redshifts have been updated to the iron release. To ensure photo-z quality of the rest of the sample without spec-z, the galaxy sample is limited to z-band apparent magnitude MAG_Z < 21. For more details on the extended halo-based group finder and sample selection, please refer to Yang et al. (2021).

Data Access

Data URL: https://data.desi.lbl.gov/public/dr1/vac/dr1/gfinder/

NERSC access for DESI collaborators:

/global/cfs/cdirs/desi/public/dr1/vac/dr1/gfinder/

Documentation

Files

• DESIDR9.y1.v1_galaxy.fits: Galaxy catalog
• DESIDR9.y1.v1_group.fits: Catalog of group properties
• iDESIDR9.y1.v1_1.fits: Galaxy-group relationship

Data Model

DESIDR9.y1.v1_galaxy.fits

EXTNAME = GALAXY

Name	Type	Units	Description
IGAL	int64		Unique id of galaxy
RA	float64	deg	Right ascension at equinox J2000
DEC	float64	deg	Declination at equinox J2000
Z	float64		Redshift
ZERR	float64		Redshift Error
ZSRC	int64		Source of Redshift. 0: ‘PHOTZ’; >0: ‘SPECZ’
MAG_Z	float64	mag	mag_z = 22.5 - 2.5log10(FLUX_Z/MW_TRANSMISION_Z)
KCORR_Z_05	float64	mag	kcorrect to z = 0.5
RELEASE	int64		from LS DR9
BRICKID	int64		from LS DR9
OBJID	int64		from LS DR9

DESIDR9.y1.v1_group.fits

EXTNAME = GROUP

Name	Type	Units	Description
IGRP	int64		Unique id of group
RICH	int64		Richness of group
GRP_RA	float64	deg	Right ascension of group
GRP_DEC	float64	deg	Declination of group
GRP_Z	float64		redshift of group
GRP_LOGM	float64		the log10 of halo mass (\(\log{\frac{hM}{M_{\odot}}}\))
GRP_LOGL	float64		the log10 of characteristic group luminosity (\(\log{\frac{h^2L}{L_{\odot}}}\))

iDESIDR9.y1.v1_1.fits

EXTNAME = GAL2GRP

Name	Type	Units	Description
IGAL	int64		Unique id of galaxy
IGRP	int64		Unique id of group
RANK	int64		0, central; == 1, satelite

Contact

Contact Yizhou Gu and Xiaohu Yang with any questions.