Detection of the 2175Å extinction feature in a lens galaxy at z = 0.83

Motta, V.; Mediavilla, E.; Falco, E.
Referencia bibliográfica

Astrophysics of Dust, Estes Park, Colorado, May 26 - 30, 2003. Edited by Adolf N. Witt, meeting abstract.

Fecha de publicación:
0
2003
Número de autores
3
Número de autores del IAC
1
Número de citas
0
Número de citas referidas
0
Descripción
We determine the extinction curve in the zl = 0.83 lens galaxy of the gravitational lens SBS 0909+532 from the wavelength dependence of the flux ratio between the lensed quasar images (zs = 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 2175Å feature, 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 RV = 2.1 ± 0.9 Galactic extinction curve. If we assume standard Galactic extinction laws, the estimated dust redshift of z = 0.88 ± 0.02 is in good agreement with the spectroscopic redshift of the lens galaxy. The widespread assumption that Small Magellanic Cloud extinction curves are more appropriate models for cosmological dust may be incorrect.