An improved method for the identification of galaxy systems: Measuring the gravitational redshift by Dark Matter Haloes

TL;DR

This paper presents a new halo-based method for identifying galaxy systems in redshift surveys, calibrated with simulations and applied to real data to measure gravitational redshift effects consistent with general relativity.

Contribution

The paper introduces a modified halo-based galaxy system identification algorithm and demonstrates its effectiveness in measuring gravitational redshift in galaxy clusters.

Findings

Radial velocity decrements align with general relativity predictions.

Method successfully applied to SDSS data.

Results consistent with previous measurements by Wojtak et al.

Abstract

We introduce a new method for the identification of galaxy systems in redshift surveys based on the halo model. This method is a modified version of the K-means identification algorithm developed by Yang et al (2005). We have calibrated and tested our algorithms using mock catalogs generated using the Millennium simulations (Springel et al. 2005) and applied them to the NYU-DR7 galaxy catalog (based on the SDSS datasets). Using this local sample of groups and clusters of galaxies we have measured the effect of gravitational redshift produced by their host dark matter haloes. Our results shows radial velocity decrements consistent with general relativity predictions and previous measurements by Wojtak et al (2011) in clusters of galaxies.