AAS 203rd Meeting, January 2004
Session 113 Molecules and Atoms at High Z and Low Z
Poster, Thursday, January 8, 2004, 9:20am-4:00pm, Grand Hall

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[113.05] Serendipitous Discovery of the 2175 Angstrom Dust Feature at High Redshift from the Sloan Digital Sky Survey

J. Wang, J. Ge (Penn. State), P.B. Hall (Princeton Univ.)

We report direct detection of the 2175Å absorption feature due to extinction by dust grains, which is seen in the Milky Way and Large Magellanic Cloud extinction curves but has been searched for over decades in intervening absorption systems at high redshift. Two quasars at redshifts 2< z <3 from the SDSS Data Release 1 exhibit the 2175Å bump from intervening absorption systems at zabs ~ 1.4, the first time this feature has been detected in individual intervening Mg\,II systems. The rest-frame FWHM of the absorption feature matches the expected FWHM of ~q 350Å. We investigate the possible dust grain type by applying reddening with the empirical extinction curves for the Milky Way, LMC and SMC, and with a range of E(B-V), to various composite quasar spectra from the SDSS to determine the best-fit intrinsic spectrum, extinction curve, and reddening. We further calculate the dust-to-gas ratios at the absorber redshifts to explore dust formation at high redshift.

This work was supported by NASA grants NGA5-12115, NAG5-11427, NSF AST-0138235 and the Penn State Eberly College of Science.

The author(s) of this abstract have provided an email address for comments about the abstract: jwang@astro.psu.edu

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.