Friday, October 9, 2009 - 2:00pm
Abstract. I will present the detection of intergalactic dust obtained with the SDSS and discuss its potential impact on the study of type Ia Supernovae. The detection is based on correlating the colors of ~85,000 quasars at z>1 with the position of 20 million foreground galaxies. We observe an excess reddening on scales ranging from 20 kpc to several Mpc and find the projected density of the dust to follow that of the mass (obtained from magnification measurements) but offset by 5 orders of magnitude. We quantify the amount of dust in galactic halos and the wavelength dependence of its extinction. Using these results I will revisit the value of the cosmic dust density, estimate the opacity of the Universe as a function of redshift and address its impact on the estimation of cosmological parameters from type Ia supernovae.