A Semi-Empirical Model of the Infrared Emission from Galaxies

TL;DR

This paper introduces a semi-empirical model combining radiative transfer and dust grain properties to simulate galaxy infrared spectra, aiding in understanding dust heating and star formation diagnostics.

Contribution

It develops a novel semi-empirical framework integrating dust physics and stellar spectra to produce comprehensive galaxy infrared emission models.

Findings

Model accurately predicts 8- and 24-micron luminosities.

Infrared color diagnostics can distinguish star-forming from old stellar populations up to redshift 2.

The approach links dust properties with galaxy spectral features.

Abstract

We present a semi-empirical model for the infrared emission of dust around star-forming sites in galaxies. Our approach combines a simple model of radiative transfer in dust clouds with a state-of-the-art model of the microscopic optical properties of dust grains pioneered by Draine & Li. In combination with the Starburst 99 stellar spectral synthesis package, this framework is able to produce synthetic spectra for galaxies which extend from the Lyman limit through to the far-infrared. We use it to probe how model galaxy spectra depend upon the physical characteristics of their dust grain populations, and upon the energy sources which heat that dust. We compare the predictions of our model with the 8- and 24-micron luminosities of sources in the Spitzer First Look Survey, and conclude by using the models to analyse the relative merits of various colour diagnostics in distinguishing systems out to a redshift of 2 with ongoing star formation from those with only old stellar populations.