Journal Article

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

Brice Ménard, Ryan Scranton, Masataka Fukugita and Gordon Richards

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 405, issue 2, pages 1025-1039
Published in print June 2010 | ISSN: 0035-8711
Published online June 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.16486.x
Measuring the galaxy–mass and galaxy–dust correlations through magnification and reddening

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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 ∼85 000 quasars at z > 1 with the position of 24 million galaxies at z∼ 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: Σdustr−0.8p, a distribution similar to mass. On large scales, its wavelength dependence is described by RV≃ 4.9 ± 3.2, consistent with interstellar dust. This, in turn, implies a cosmic dust density of Ωdust≃ 5 × 10−6, roughly half of which comes from dust in haloes of ∼L galaxies. We estimate the resulting opacity of the Universe for various evolutionary models and find 〈AV〉∼ 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 Σ∼ 30(θ/1 arcmin)−0.8 h M pc−2 up to a radius of 10 Mpc, in agreement with gravitational shear estimates.

Keywords: gravitational lensing: weak; dust, extinction; dark matter

Journal Article.  9984 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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