2013/03/26 by Jean Coupon, Tom Broadhurst, Keiichi Umetsu · 21 citations
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Cluster (spacecraft) #Context (archaeology) #Cosmology #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Redshift #Sky #Space Technology and Applications #Weak gravitational lensing #astro-ph.CO
paper · pdf · doi:10.1088/0004-637x/772/1/65
published in The Astrophysical Journal 772(1), 65 (IOP Publishing) · 12 pages, 6 figures, submitted to The Astrophysical Journal
arxiv created 2013/03/26 · openalex publication_date 2013/07/08 · arxiv updated 2015/06/15 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/08
We report the first detection of a redshift-depth enhancement of background galaxies magnified by foreground clusters. Using 300,000 BOSS survey galaxies with accurate spectroscopic redshifts, we measure their mean redshift depth behind four large samples of optically selected clusters from the Sloan Digital Sky Survey (SDSS) surveys, totaling 5000–15,000 clusters. A clear trend of increasing mean redshift toward the cluster centers is found, averaged over each of the four cluster samples. In addition, we find similar but noisier behavior for an independent X-ray sample of 158 clusters lying in the foreground of the current BOSS sky area. By adopting the mass–richness relationships appropriate for each survey, we compare our results with theoretical predictions for each of the four SDSS cluster catalogs. The radial form of this redshift enhancement is well fitted by a richness-to-mass weighted composite Navarro–Frenk–White profile with an effective mass ranging between M 200 ∼ 1.4–1.8 × 10 14 M ☉ for the optically detected cluster samples, and M 200 ∼ 5.0 × 10 14 M ☉ for the X-ray sample. This lensing detection helps to establish the credibility of these SDSS cluster surveys, and provides a normalization for their respective mass–richness relations. In the context of the upcoming bigBOSS, Subaru Prime Focus Spectrograph, and EUCLID-NISP spectroscopic surveys, this method represents an independent means of deriving the masses of cluster samples for examining the cosmological evolution, and provides a relatively clean consistency check of weak-lensing measurements, free from the systematic limitations of shear calibration.