eBOSS LRG Target Selection
This page summarizes the eBOSS luminous red galaxy sample, denoted LRG1_WISE in the target selection bitmask EBOSS_TARGET1. A small amount of fibers are allocated for subclass of targets denoted by LRG1_IDROP in the same bitmask. For detailed information on LRG target selection in eBOSS, please see Prakash et al (2016)
Whilst reading this page please keep in mind the following important, and occasionally subtle, points:
- Unless specified differently, in what follows all colors and magnitudes are computed using model magnitudes.
- All quantities are corrected for Galactic extinction following Schlegel, Finkbeiner & Davis (1998).
- All objects are PRIMARY.
The eBOSS LRG1_WISE Galaxy Sample
eBOSS selects galaxies are higher redshift than the BOSS galaxy sample by using a combination of SDSS imaging data combined with infrared imaging data from the WISE satellite. The selection cuts below achieve a median redshift of z~0.7, with a peak number of density of ~0.0003 per cubic Mpc.
eBOSS targets galaxies that are fainter than BOSS. Targets are restricted to the following flux limits:
- 19.9 ≤ i ≤ 21.8
- z ≤ 19.95
- W1 ≤ 20.299
The selection cuts are as follows:
- r – i > 0.98
- r – W1 > 2.0 × (r – i)
- i – z > 0.625
Equations (1) and (2) represent the basic LRG target selection and define the bulk of the LRG sample; Eq. (1) isolates the desired redshift range, while Eq. (2) serves to attenuate stellar contamination. Equation (3) helps reduce to number of interlopers from z < 0.6. W1 is the 3.4 micron WISE imaging band.