Measuring the galaxy-mass and galaxy-dust correlations through magnification and reddening

We present a simultaneous detection of gravitational magnification and dust reddening effects due to galactic haloes and large-scale structure. The measurement is based on correlating the brightness of similar to 85 000 quasars at z > 1 with the position of 24 million galaxies at z similar to 0.3 derived from the Sloan Digital Sky Survey and is used to constrain the galaxy-mass and galaxy-dust correlation functions up to cosmological scales. The presence of dust is detected from 20 kpc to several Mpc, and we find its projected density to follow: Sigma(dust) similar to r-0.8(p), a distribution similar to mass. On large scales, its wavelength dependence is described by R(V) similar or equal to 4.9 +/- 3.2, consistent with interstellar dust. This, in turn, implies a cosmic dust density of (dust) similar or equal to 5 x 10-6, roughly half of which comes from dust in haloes of similar to L star galaxies. We estimate the resulting opacity of the Universe for various evolutionary models and find << A(V) >> similar to 0.03 mag up to z = 0.5. We present magnification measurements, corrected for dust extinction, from which the galaxy-mass correlation function is inferred to give the mean surface mass density profile around galaxies Sigma similar to 30(theta /1 arcmin)-0.8 h M(circle dot) pc-2 up to a radius of 10 Mpc, in agreement with gravitational shear estimates.