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arXiv · 1003.0030

Two Lensed z~3 Lyman Break Galaxies Discovered in the SDSS Giant Arcs Survey

Benjamin P. Koester·Michael D. Gladders·Joseph F. Hennawi·Keren Sharon·Eva Wuyts·J. R. Rigby·Matthew B. Bayliss·Hakon Dahle
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Abstract

We report the discovery of two strongly-lensed z ~ 3 Lyman Break Galaxies (LBGs) discovered as u-band dropouts as part of the SDSS Giant Arcs Survey (SGAS). The first, SGAS J122651.3+215220 at z = 2.9233 is lensed by one of several sub-clusters, SDSS J1226+2152, in a complex massive cluster at z = 0.43. Its (g, r, i) magnitudes are (21.14, 20.60, 20.51) which translate to surface brightnesses, mu_{g,r,i}, of (23.78, 23.11, 22.81). The second, SGAS J152745.1+065219, is an LBG at z = 2.7593 lensed by the foreground SDSS J1527+0652 at z = 0.39, with (g, r, z)=(20.90, 20.52, 20.58) and mu_{g,r,z}=(25.15, 24.52, 24.12). Moderate resolution spectroscopy confirms the redshifts suggested by photometric breaks, and shows both absorption and emission features typical of LBGs. Lens mass models derived from combined imaging and spectroscopy reveal that SGAS J122651.3+215220 is a highly magnified source (M ~40), while SGAS J152745.1+065219 is magnified by no more than M ~ 15. Compared to LBG survey results (Steidel et al. 2003), the luminosities and lensing-corrected magnitudes suggest that SGAS J122651.3+215220 is among the faintest 20% of LBGs in that sample. SGAS J152745.1+065219, on the other hand, appears to be more representative of the average LBG, similar to the "Cosmic Eye".

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Benjamin P. Koester, Michael D. Gladders, Joseph F. Hennawi, Keren Sharon, Eva Wuyts, J. R. Rigby, Matthew B. Bayliss, Hakon Dahle. 2010-03-15. Two Lensed z~3 Lyman Break Galaxies Discovered in the SDSS Giant Arcs Survey. https://doi.org/10.1088/2041-8205%2F723%2F1%2Fl73

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