4098 galaxy clusters to z~0.6 in the Sloan Digital Sky Survey equatorial Stripe 82

TL;DR

This paper presents a catalog of over 4000 galaxy clusters up to redshift 0.6 in the SDSS Stripe 82 region, utilizing deeper multi-epoch photometry and an overdensity detection algorithm, with implications for galaxy evolution and quasar absorption studies.

Contribution

The study introduces a new galaxy cluster catalog based on multi-epoch SDSS data and a Voronoi tessellation overdensity detection method, extending the redshift range and depth of previous surveys.

Findings

Catalog contains 4098 clusters with median redshift 0.32.

32% of clusters have spectroscopic redshifts; others have accurate photometric redshifts.

Linked quasar sight-lines enable studies of MgII absorption in cluster environments.

Abstract

We present a catalogue of 4098 photometrically selected galaxy clusters with a median redshift <z> = 0.32 in the 270 square degree 'Stripe 82' region of the Sloan Digital Sky Survey (SDSS), covering the celestial equator in the Southern Galactic Cap (-50 < RA < 59 deg, |Dec| < 1.25 deg). Owing to the multi-epoch SDSS coverage of this region, the ugriz photometry is ~2 magnitudes deeper than single scans within the main SDSS footprint. We exploit this to detect clusters of galaxies using an algorithm that searches for statistically significant overdensities of galaxies in a Voronoi tessellation of the projected sky. 32% of the clusters have at least one member with a spectroscopic redshift from existing public data (SDSS Data Release 7, 2SLAQ & WiggleZ), and the remainder have a robust photometric redshift (accurate to ~5-9% at the median redshift of the sample). The weighted average of the member galaxies' redshifts provides a reasonably accurate estimate of the cluster redshift. The cluster catalogue is publicly available for exploitation by the community to pursue a range of science objectives. In addition to the cluster catalogue, we provide a linked catalogue of 18,295 V<21 mag quasar sight-lines with impact parameters within <3 Mpc of the cluster cores selected from the catalogue of Veron et al. (2010). The background quasars cover 0.25 < z < 2, where MgII absorption-line systems associated with the clusters are detectable in optical spectra.