Producing a BOSS CMASS sample with DES imaging

Abstract

We present a sample of galaxies with the Dark Energy Survey (DES) photometry that replicates the properties of the BOSS CMASS sample. The CMASS galaxy sample has been well characterized by the Sloan Digital Sky Survey (SDSS) collaboration and was used to obtain the most powerful redshift-space galaxy clustering measurements to date. A joint analysis of redshift-space distortions (such as those probed by CMASS from SDSS) and a galaxy-galaxy lensing measurement for an equivalent sample from DES can provide powerful cosmological constraints. Unfortunately, the DES and SDSS-BOSS footprints have only minimal overlap, primarily on the celestial equator near the SDSS Stripe 82 region. Using this overlap, we build a robust Bayesian model to select CMASS-like galaxies in the remainder of the DES footprint. The newly defined DES-CMASS (DMASS) sample consists of 117,293 effective galaxies covering 1, 244 deg 2 . Through various validation tests, we show that the DMASS sample selected by this model matches well with the BOSS CMASS sample, specifically in the South Galactic cap (SGC) region that includes Stripe 82. Combining measurements of the angular correlation function and the clustering-z distribution of DMASS, we constrain the difference in mean galaxy bias and mean redshift between the BOSS CMASS and DMASS samples to be ∆b = 0.010 +0.045 −0.052 and ∆z = 3.46 +5.48 −5.55 × 10 −3 for the SGC portion of CMASS, and ∆b = 0.044 +0.044 −0.043 and ∆z = (3.51 +4.93 −5.91 ) × 10 −3 for the full CMASS sample. These values indicate that the mean bias of galaxies and mean redshift in the DMASS sample is consistent with both CMASS samples within 1σ.

Debris Disk Results from the Gemini Planet Imager Exoplanet Survey's Polarimetric Imaging Campaign

“…The remaining targets generally have age range estimates based on lithium abundance and chromospheric activity for lower-mass stars, and evolution across the color-magnitude diagram for higher-mass stars; see Nielsen et al (2019) for details. We note that 13 stars 40 from this latter group were recently associated with moving groups based on a re-evaluation of their kinematic information via the methods presented in Lee & Song (2019) and may have different ages (mostly younger) from those we report here.…”

Constraining early dark energy with large-scale structure

“…This is due to a small sky overlap, different survey depths, and different photo-z calibration, which diminishes the impact of a possible common systematic. As far as the covariance between BOSS and WL surveys is concerned, the sky overlap between BOSS and the DES-Y1, KV450, and HSC footprints is only 1%, 2%, and 1.5% [79][80][81] of the total BOSS footprint, respectively; hence, the cross-covariance is negligibly small as well.…”

The HOSTS Survey: Evidence for an Extended Dust Disk and Constraints on the Presence of Giant Planets in the Habitable Zone of β Leo

“…The age of this moving group can be determined relatively accurately from isochrones, lithium abundances, etc. for the lower-mass members and is believed to be 55-70 Myr (with uncertainties due to possible contamination; Bell et al 2015), 40-50 Myr (Zuckerman 2019), or 30-40 Myr (Lee & Song 2019). If this membership assignment is correct, then a rough lower limit to the age is 50 Myr.…”