Non-Gaussian velocity distributions - The effect on virial mass estimates of galaxy groups

TL;DR

This study investigates how non-Gaussian velocity distributions in galaxy groups affect virial mass estimates, revealing that non-Gaussian groups are more massive and often multimodal, impacting cosmological mass function analyses.

Contribution

It demonstrates that non-Gaussian galaxy groups are typically more massive and composed of multiple velocity modes, highlighting the importance of considering multimodality in mass estimates.

Findings

Non-Gaussian groups have significantly higher masses than Gaussian groups.

All non-Gaussian groups tend to be multimodal, with multiple velocity components.

Multimodal groups have mass distributions similar to Gaussian groups.

Abstract

We present a study of 9 galaxy groups with evidence for non-Gaussianity in their velocity distributions out to 4R200. This sample is taken from 57 groups selected from the 2PIGG catalog of galaxy groups. Statistical analysis indicates that non-Gaussian groups have masses significantly higher than Gaussian groups. We also have found that all non-Gaussian systems seem to be composed of multiple velocity modes. Besides, our results indicate that multimodal groups should be considered as a set of individual units with their own properties. In particular, we have found that the mass distribution of such units are similar to that of Gaussian groups. Our results reinforce the idea of non-Gaussian systems as complex structures in the phase space, likely corresponding to secondary infall aggregations at a stage before virialization. The understanding of these objects is relevant for cosmological studies using groups and clusters through the mass function evolution.