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

Authors

  • James E. Geach,

    Corresponding author
    1. Department of Physics, McGill University, Ernest Rutherford Building, 3600 Rue University, Montreal, Quebec H3A 2T8, Canada
    2. Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE
      E-mail: jimgeach@physics.mcgill.ca
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  • David N. A. Murphy,

    1. Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE
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  • Richard G. Bower

    1. Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE
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E-mail: jimgeach@physics.mcgill.ca

ABSTRACT

We present a catalogue of 4098 photometrically selected galaxy clusters with a median redshift z〉= 0.32 in the 270 deg2‘Stripe 82’ region of the Sloan Digital Sky Survey (SDSS), covering the celestial equator in the Southern Galactic Cap (−50° < α < 59°, |δ| ≤ 1bsl0006425). Owing to the multi-epoch SDSS coverage of this region, the ugriz photometry is ∼2 mag 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 per cent of the clusters have at least one member with a spectroscopic redshift from existing public data (SDSS Data Release 7, 2SLAQ and WiggleZ), and the remainder have a robust photometric redshift (accurate to ∼5–9 per cent 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 sightlines with impact parameters within ≤3 Mpc of the cluster cores selected from the catalogue of Veron-Cetty & Veron (2010). The background quasars cover 0.25 < z < 2, where Mg ii absorption-line systems associated with the clusters are detectable in optical spectra.

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