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  • BROADBAND PHOTOMETRY OF 105...
    Bayliss, Matthew B

    Astrophysical journal. Letters, 01/2012, Letnik: 744, Številka: 2
    Journal Article

    We measure the photometric properties of 105 giant arcs that were identified in systematic searches for galaxy-cluster-scale strong lenses in the Second Red-Sequence Cluster Survey and the Sloan Digital Sky Survey. The cluster lenses span 0.2 < z sub(l) < 1.2 in redshift, with a median z sub(l) = 0.58. Using broadband color criteria we sort the entire arc sample into redshift bins based on u-g and g-r colors, and also r-z colors for the ~90% of arcs that have z-band data. This analysis yields broad redshift constraints with 71 sub(-4) super(+5)% of the arcs at z > or = 1.0, 64 sub(-4) super(+6)% at z > 1.4, 56 sub(-4) super(+5)% at z > or = 1.9, and 21 sub(-2) super(+4)% at z > or = 2.7. The remaining 29 sub(-5) super(+03)% have z < 1. The inferred median redshift is z sub(s) = 2.0 + or - 0.1, in good agreement with a previous determination from a smaller sample of brighter arcs (g <, approximate 22.5). This agreement confirms that z sub(s) = 2.0 + or - 0.1 is the typical redshift for giant arcs with g <, approximate 24 that are produced by cluster-scale strong lenses and that there is no evidence for strong evolution in the redshift distribution of arcs over a wide range of g-band magnitudes (20 < or = g < or = 24). Establishing that half of all giant arcs are at z >, approximate 2 contributes significantly toward relieving the tension between the number of arcs observed and the number expected in a ACDM cosmology, but there is considerable evidence to suggest that a discrepancy persists. Additionally, this work confirms that forthcoming large samples of giant arcs will supply the observational community with many magnified galaxies at z >, approximate 2.