Cosmology with all-sky surveys

TL;DR

This paper discusses the use of all-sky surveys like 2MASS, WISE, and SuperCOSMOS to create large photometric redshift catalogs, enabling extensive cosmological studies of the universe's structure, dark energy, and dark matter.

Contribution

It introduces a comprehensive methodology for constructing large-scale photometric redshift catalogs from multiple surveys, facilitating advanced cosmological research.

Findings

The 2MASS Photometric Redshift catalog (2MPZ) includes nearly 1 million galaxies.

Combining WISE and SuperCOSMOS data extends depth to over 1 Gpc.

These catalogs enable tests of the Copernican Principle and dark energy properties.

Abstract

Various aspects of cosmology require comprehensive all-sky mapping of the cosmic web to considerable depths. In order to probe the whole extragalactic sky beyond 100 Mpc, one must draw on multiwavelength datasets and state-of-the-art photometric redshift techniques. Here I summarize our dedicated program that employs the largest photometric all-sky surveys -- 2MASS, WISE and SuperCOSMOS -- to obtain accurate redshift estimates of millions of galaxies. The first outcome of these efforts -- the 2MASS Photometric Redshift catalog (2MPZ) -- was publicly released in 2013 and includes almost 1 million galaxies with a median redshift of z~0.1. I discuss how this catalog was constructed and how it is being used for various cosmological tests. I also present how combining the WISE mid-infrared survey with SuperCOSMOS optical data allowed us to push to depths over 1 Gpc on unprecedented angular scales. These photometric redshift samples, with about 20 million sources in total, provide access to volumes large enough to study observationally the Copernican Principle of universal homogeneity and isotropy, as well as to probe various aspects of dark energy and dark matter through cross-correlations with other data such as the cosmic microwave or gamma-ray backgrounds. Last but not least, they constitute a test-bed for forthcoming wide-angle multi-million galaxy samples expected from such instruments as the SKA, Euclid, or LSST.