A WISE view of the composite luminosity function of cluster members

TL;DR

This paper constructs a composite luminosity function for galaxy cluster members using WISE survey data, revealing characteristic features and trends with redshift, aiding future cluster detection methods.

Contribution

It presents the first characterization of the WISE-based luminosity function of redMaPPer cluster members, providing a new tool for cluster detection algorithms.

Findings

Galaxy cluster members have a characteristic luminosity function with a slope change at a certain magnitude.

The bright-end slope remains constant at 3.54 across redshifts.

The faint-end slope varies from 2 to 3, increasing with redshift.

Abstract

Galaxy clusters play a crucial role in constraining cosmological parameters. Cluster detection and characterization have therefore become an important field of modern cosmology. In this work, we aim at constructing reasonably representative composite luminosity function of cluster members in the WISE survey that can be used in the future as an input in matching algorithms for cluster detection. We use a sample of massive clusters from the redMaPPer catalog to match the positions of the WISE sources. We build the composite luminosity function of the WISE members in different redshift bins. We find that galaxy cluster members have a characteristic composite luminosity function, with a clear change in the slope at a given magnitude apparent $M^{*}$, which becomes fainter with increasing redshift. The best-fit bright-end slope $\beta$ is compatible with a constant value of $3.54$ with no clear trend with redshift, while the faint-end slope $\alpha$ is remarkably different, ranging from $2$ to $3$. We present the first characterization of the composite luminosity function of the WISE counterparts of redMaPPer cluster members and in this way we provide an element for building cluster detection techniques based on matching algorithms.