The 2M++ galaxy redshift catalogue

TL;DR

The paper introduces 2M++, a comprehensive galaxy redshift catalogue covering nearly the entire sky up to 200 Mpc/h, enabling better understanding of large-scale structures and local galaxy motions.

Contribution

It provides a new, deep all-sky galaxy redshift compilation combining multiple surveys, with methods to correct for incompleteness and a detailed density field analysis.

Findings

Mapping of large-scale structures like the Shapley Concentration.

Assessment and correction of redshift incompleteness.

Density field characterization of the Local Universe.

Abstract

Peculiar velocities arise from gravitational instability, and thus are linked to the surrounding distribution of matter. In order to understand the motion of the Local Group with respect to the Cosmic Microwave Background, a deep all-sky map of the galaxy distribution is required. Here we present a new redshift compilation of 69~160 galaxies, dubbed 2M++, to map large-scale structures of the Local Universe over nearly the whole sky, and reaching depths of K <= 12.5, or 200 Mpc/h. The target catalogue is based on the Two-Micron-All-Sky Extended Source Catalog (2MASS-XSC). The primary sources of redshifts are the 2MASS Redshift Survey, the 6dF galaxy redshift survey and the Sloan Digital Sky Survey (DR7). We assess redshift completeness in each region and compute the weights required to correct for redshift incompleteness and apparent magnitude limits, and discuss corrections for incompleteness in the Zone of Avoidance. We present the density field for this survey, and discuss the importance of large-scale structures such as the Shapley Concentration.