Density Jumps Near the Virial Radius of Galaxy Clusters

TL;DR

This study investigates the presence of steep density jumps near the virial radius in galaxy clusters by analyzing galaxy distribution data, testing simulation predictions with observational data.

Contribution

It demonstrates the potential to detect density jumps in galaxy clusters using current datasets and fitting methods, providing a basis for future detailed analyses.

Findings

Some clusters show strong evidence for a density jump.

The analysis supports simulation predictions of steep density features.

Methodology includes parametric and non-parametric approaches.

Abstract

Recent simulations have indicated that the dark matter halos of galaxy clusters should feature steep density jumps near the virial radius. Since the member galaxies are expected to follow similar collisionless dynamics as the dark matter, the galaxy density profile should show such a feature as well. We examine the potential of current datasets to test this prediction by selecting cluster members for a sample of 56 low-redshift (0.1<z<0.3) galaxy clusters, constructing their projected number density profiles, and fitting them with two profiles, one with a steep density jump and one without. Additionally, we investigate the presence of a jump using a non-parametric spline approach. We find that some of these clusters show strong evidence for a model with a density jump. We discuss avenues for further analysis of the density jump with future datasets.