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arXiv · astro-ph/0204130

Detection of the 2175ÅExtinction Feature at z=0.83

V. Motta·E. Mediavilla·J. A. Munoz·E. Falco·C. S. Kochanek·S. Arribas·B. Garcia-Lorenzo·A. Oscoz·M. Serra-Ricart
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Abstract

We determine the extinction curve in the z_l=0.83 lens galaxy of the gravitational lens SBS0909+532 from the wavelength dependence of the flux ratio between the lensed quasar images (z_s=1.38) from 3400 to 9200Å. It is the first measurement of an extinction curve at a cosmological distance of comparable quality to those obtained within the Galaxy. The extinction curve has a strong 2175Åfeature, a noteworthy fact because it has been weak or non-existent in most estimates of extinction curves outside the Galaxy. The extinction curve is fitted well by a standard $R_V=2.1\pm0.9$ Galactic extinction curve. If we assume standard Galactic extinction laws, the estimated dust redshift of $z=0.88\pm0.02$ is in good agreement with the spectroscopic redshift of the lens galaxy. The widespread assumption that SMC extinction curves are more appropriate models for cosmological dust may be incorrect.

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V. Motta, E. Mediavilla, J. A. Munoz, E. Falco, C. S. Kochanek, S. Arribas, B. Garcia-Lorenzo, A. Oscoz, M. Serra-Ricart. 2002-04-08. Detection of the 2175ÅExtinction Feature at z=0.83. https://doi.org/10.1086/341118

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