The Dust Content of Galaxy Clusters

TL;DR

This study detects and characterizes dust in galaxy clusters at z ~ 0.2 through reddening measurements, revealing dust presence mainly at outskirts and confirming gravitational magnification effects consistent with theoretical models.

Contribution

First measurement of dust reddening in galaxy clusters at z ~ 0.2 using SDSS data, highlighting dust distribution and gravitational lensing effects.

Findings

Mean E(B-V) of a few times 10^-3 mag near cluster outskirts

Shallow radial dependence of dust extinction

Gravitational magnification of background sources aligns with predictions

Abstract

We report on the detection of reddening toward z ~ 0.2 galaxy clusters. This is measured by correlating the Sloan Digital Sky Survey cluster and quasar catalogs and by comparing the photometric and spectroscopic properties of quasars behind the clusters to those in the field. We find mean E(B-V) values of a few times 10^-3 mag for sight lines passing ~Mpc from the clusters' center. The reddening curve is typical of dust but cannot be used to distinguish between different dust types. The radial dependence of the extinction is shallow near the cluster center suggesting that most of the detected dust lies at the outskirts of the clusters. Gravitational magnification of background z ~ 1.7 sources seen on Mpc (projected) scales around the clusters is found to be of order a few per cent, in qualitative agreement with theoretical predictions. Contamination by different spectral properties of the lensed quasar population is unlikely but cannot be excluded.