Speaker
Description
We present a new two-component dust geometry model of disk galaxies, the Chocolate Chip Cookie (CCC) model, where the clumpy nebular regions are embedded in a diffuse stellar/interstellar medium disk, like chocolate chips in a cookie. Our model solves the dust attenuation process for both the emission lines and stellar continua via analytical approaches, which successfully fits the inclination dependence of both the effective dust reddening of the stellar components and that of the emission lines characterized by the Balmer decrement. In CCC model, the dust attenuation curve of the stellar population naturally depends on the inclination, and its median case is consistent with the classical Calzetti law. Not only that, our model shows that the dust-to-gas ratio (DGR) of clumpy HII regions increases monotonically with the stellar mass of galaxies. At a given stellar mass, DGR shows a linear correlation with the gas-phase metallicity, which implies a constant dust-to-metal ratio of galaxies at a given stellar mass. Our CCC model provides a sophisticated framework of the galactic dust attenuation of disk galaxies, which can be applied in numerical simulations or semi-analytical models of galaxy formation and evolution.
