Probing clustering features around Cl 0024+17

TL;DR

This paper analyzes the spatial distribution of galaxies around Cl 0024+17 to identify significant physical scales, using advanced statistical methods, and finds two key scales related to dark matter features and possible galaxy clumps.

Contribution

It introduces a generalized spatial analysis method for non-stationary point patterns to study galaxy distributions around clusters.

Findings

Identifies two significant physical scales at 31.4 and 112.9 arcseconds.

Finds the second scale aligns with the dark matter ring radius.

Suggests a galaxy clump may influence the second transition scale.

Abstract

I present a spatial analysis of the galaxy distribution around the cluster Cl 0024+17. The basic aim is to find the scales where galaxies present a significant deviation from an inhomogeneous Poisson statistical process. Using the generalization of the Ripley, Besag, and the pair correlation functions for non-stationary point patterns, I estimate these transition scales for a set of 1,000 Monte Carlo realizations of the Cl 0024+17 field, corrected for completeness up to the outskirts. The results point out the presence of at least two physical scales in this field at 31.4 and 112.9 arcseconds. The second one is statistically consistent with the dark matter ring radius (about 75 arcseconds) previously identified by Jee et al. (2007). However, morphology and anisotropy tests point out that a clump at about 120 arcseconds NW from the cluster center could be the responsible for the second transition scale. These results do not indicate the existence of a galaxy counterpart of the dark matter ring, but the methodology developed to study the galaxy field as a spatial point pattern provides a good statistical evaluation of the physical scales around the cluster. I briefly discuss the usefulness of this approach to probe features in galaxy distribution and N-body dark matter simulation data.