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 ( 18 ) .
We assume that the dust distribution around a galaxy is described by a simple power law , similarly to the mass distribution , but with a sharp cut-off at \alpha R _ { vir } where R _ { vir } is the galaxy ’ s virial radius and \alpha is a model parameter .
Our model reproduces the observed dust distribution profile very well over a wide range of radial distance of 10 - 10 ^ { 4 } h ^ { -1 } kpc .
For the characteristic galaxy halo mass of 2 \times 10 ^ { 12 } h ^ { -1 } M _ { \odot } estimated for the SDSS galaxies , the best fit model is obtained if \alpha is greater than unity , which suggests that dust is distributed to over a few hundred kilo-parsecs 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 .