Mapping the Cosmic Web with the largest all-sky surveys

TL;DR

This paper discusses the creation of large, multiwavelength photometric redshift catalogs that enable detailed three-dimensional mapping of the low-redshift Cosmic Web across the entire sky, surpassing previous depth and coverage limitations.

Contribution

It introduces a new methodology combining multiple all-sky surveys and photometric redshift techniques to produce extensive galaxy catalogs for cosmological studies.

Findings

Public release of the 2MASS Photometric Redshift catalog with nearly 1 million galaxies.

Expansion of redshift coverage to z~0.2--0.3 on large angular scales.

Enabling studies of local galaxy flows and cross-correlations with the CMB.

Abstract

Our view of the low-redshift Cosmic Web has been revolutionized by galaxy redshift surveys such as 6dFGS, SDSS and 2MRS. However, the trade-off between depth and angular coverage limits a systematic three-dimensional account of the entire sky beyond the Local Volume (z<0.05). In order to reliably map the Universe to cosmologically significant depths over the full celestial sphere, one must draw on multiwavelength datasets and state-of-the-art photometric redshift techniques. We have undertaken a dedicated program of cross-matching 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, Bilicki et al. 2014a) -- has been publicly released and includes almost 1 million galaxies with a mean redshift of z=0.08. Here we summarize how this catalog was constructed and how using the WISE mid-infrared sample together with SuperCOSMOS optical data allows us to push to redshift shells of z~0.2--0.3 on unprecedented angular scales. Our catalogs, with ~20 million sources in total, provide access to cosmological volumes crucial for studies of local galaxy flows (clustering dipole, bulk flow) and cross-correlations with the cosmic microwave background such as the integrated Sachs-Wolfe effect or lensing studies.