Distribution of Dust around Galaxies: An Analytic Model

TL;DR

This paper presents an analytic halo model for dust distribution around galaxies, successfully matching observed profiles from SDSS data and suggesting dust extends over hundreds of kiloparsecs.

Contribution

The paper introduces a simple power-law analytic model for dust distribution around galaxies, fitting observational data and linking dust extent to stellar evolution estimates.

Findings

Model reproduces observed dust profiles from 10 to 10^4 h^{-1}kpc.

Dust extends over a few hundred kiloparsecs from galaxies.

Total dust amount aligns with stellar evolution estimates.

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 Menard et al.(2010). 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 $\alpha R_{\rm vir}$ where $R_{\rm vir}$ 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.