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Keywords:

  • galaxies: haloes;
  • intergalactic medium;
  • dark matter;
  • large scale of Universe

ABSTRACT

We develop an analytic halo model for the distribution of dust around galaxies. The model results are compared with the observed surface dust density profile measured through reddening of background quasars in the Sloan Digital Sky Survey (SDSS) reported by Ménard et al. We assume that the dust distribution around a galaxy is described by a simple power law, similar to the mass distribution, but with a sharp cut-off at αRvir, where Rvir is the galaxy’s virial radius and α is a model parameter. Our model reproduces the observed dust distribution profile very well over a wide range of radial distance of 10–104 h−1 kpc. For the characteristic galaxy halo mass of 2 × 1012 h−1 M estimated for the SDSS galaxies, the best-fitting model is obtained if α is greater than unity, which suggests that dust is distributed to over a few hundred kiloparsecs from the galaxies. The observed large-scale dust distribution profile is reproduced if we assume the total amount of dust is equal to that estimated from the integrated stellar evolution over the cosmic time.