Photometric Selection of a Massive Galaxy Catalog with $z\geq0.55$

TL;DR

This paper develops a large photometrically selected galaxy catalog targeting high-redshift massive galaxies, using optical and infrared data, with detailed redshift and color analysis to assess its composition and contamination.

Contribution

The paper introduces a new method for selecting massive galaxies at $z extgreater 0.55$ using combined optical and infrared color cuts, optimized with ROC curves, resulting in a large, well-characterized catalog.

Findings

Catalog contains over 16 million objects over SDSS DR10 footprint.

Average redshift of the catalog is approximately 0.6-0.65.

Estimated 34% of the catalog are blue galaxies at $z extgreater 0.55$.

Abstract

We present the development of a photometrically selected massive galaxy catalog, targeting Luminous Red Galaxies (LRGs) and massive blue galaxies at redshifts $z\geq 0.55$. Massive galaxy candidates are selected using infrared/optical color-color cuts, with optical data from Sloan Digital Sky Survey (SDSS) and infrared data from "unWISE" forced photometry derived from the Wide-field Infrared Survey Explorer (WISE). The selection method is based on previously developed techniques to select LRGs with $z>0.5$, and is optimized using receiver operating characteristic (ROC) curves. The catalog contains 16,191,145 objects, selected over the full SDSS DR10 footprint. The redshift distribution of the resulting catalog is estimated using spectroscopic redshifts from the DEEP2 Galaxy Redshift Survey and photometric redshifts from COSMOS. Restframe $U-B$ colors from DEEP2 are used to estimate LRG selection efficiency. Using DEEP2, the resulting catalog has average redshift $z=0.65$, with standard deviation $\sigma = 2.0$, and average restframe $U-B=1.0$, with standard deviation $\sigma=0.27$. Using COSMOS, the resulting catalog has average redshift $z=0.60$, with standard deviation $\sigma = 1.8$. We estimate 34% of the catalog to be blue galaxies with $z\geq0.55$. An estimated 9.6% of selected objects are blue sources with redshift $z<0.55$. Stellar contamination is estimated to be 1.8%.