Vindicating single-T modified blackbody fits to Herschel SEDs (Research Note)

TL;DR

This paper demonstrates that simplified single-temperature modified blackbody fits to Herschel data can reliably estimate galaxy dust mass, provided the absorption cross section and spectral index are consistently chosen, aligning with full dust models.

Contribution

It validates the use of simpler blackbody fits for dust mass estimation by showing their consistency with comprehensive dust models when parameters are properly aligned.

Findings

Single blackbody fits yield accurate dust mass estimates.

Consistency in absorption cross section and spectral index is crucial.

Dust mass is insensitive to the choice of beta if parameters are matched.

Abstract

I show here that the bulk of the dust mass in a galaxy can be equivalently estimated from: i) the full spectral energy distribution of dust emission, using the approach of Draine & Lee (2007) that includes a distribution of dust grains and a range of interstellar radiation field intensities; ii) the emission in the wavelength range 100um <= lambda <= 500um (covered by the Herschel Space Observatory), by fitting to the data a simpler single temperature modified blackbody. Recent claims on the contrary (Dale et al. 2012) should be interpreted as a caveat to use in the simpler fits an absorption cross section which is consistent both in the normalization and in the spectral index beta with that of the full dust model. I also show that the dust mass does not depend significantly on the choice of beta, if both the dust mass and the absorption cross section are derived with the same assumption on beta.