AAS 207th Meeting, 8-12 January 2006
Session 120 Intergalactic Medium and Absorption Line Systems
Poster, Wednesday, 9:20am-6:30pm, January 11, 2006, Exhibit Hall

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[120.01] Average Extinction Curves and Abundances at 1

D.E. Vanden Berk (PSU), D.G. York (Chicago), P. Khare (Utkal), V.P. Kulkarni (South Carolina), A.P.S. Crotts (Columbia), J.T. Lauroesch (Northwestern), G.T. Richards, C.-W. Yip (JHU), D.P. Schneider (PSU), D. Welty, Y. Alsayyad, N. Shanidze, J. Vanlandingham, J. Tumlinson (Chicago), A. Kumar (NYU), B. Lundgren (Illinois), B. Baugher (UCSB), P.B. Hall (York), E.B. Jenkins (Princeton), B. Menard (IAS), S. Rao, D. Turnshek (Pittsburgh), J. Brinkman (APO), SDSS Collaboration

We present average extinction curves and relative abundance measurements for a sample of 809 MgII absorption line systems, with 1.0 < zabs < 1.86, identified in the spectra of SDSS quasars. Extinction curves for numerous sub-samples were generated by comparing geometric mean absorber-frame spectra with those of matching quasar spectra without absorbers. There is clear evidence for the presence of dust in the intervening systems. All of the extinction curves are similar to the SMC extinction curve, and the 2175{Å} absorption feature is not detectable in the curves of any of the sub-samples. Quasars with absorbers are at least three times as likely to have highly reddened spectra, compared to quasars without detected absorption systems. The average absorber-frame color excess, E(B-V), ranges from <0.001 to 0.085, and depends on the properties of the absorbers in the sub-samples. The column densities of numerous first ions do not show as correspondingly large a variation as the color excess. The depletion pattern in the high E(B-V) samples is similar to that of Galactic halo clouds, and is consistent with those found for individual damped Ly\,\alpha systems.

Funding for the Sloan Digital Sky Survey (SDSS) has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, the Max Planck Society, and the HEFCE.

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