HERschel Observations of Edge-on Spirals (HEROES). III. Dust energy balance study of IC 2531

TL;DR

This study models the dust energy balance in the edge-on galaxy IC 2531 using advanced radiative transfer techniques, revealing persistent discrepancies and the impact of dust models on infrared emission predictions.

Contribution

First to incorporate near-infrared imaging into detailed radiative transfer modeling of IC 2531, improving dust parameter constraints and comparing dust models' effects on infrared emission.

Findings

Near-infrared imaging improves dust parameter constraints.

Model underestimates far-infrared flux by a factor of two.

The THEMIS dust model better reproduces infrared emission.

Abstract

We investigate the dust energy balance for the edge-on galaxy IC 2531, one of the seven galaxies in the HEROES sample. We perform a state-of-the-art radiative transfer modelling based, for the first time, on a set of optical and near-infrared galaxy images. We show that taking into account near-infrared imaging in the modelling significantly improves the constraints on the retrieved parameters of the dust content. We confirm the result from previous studies that including a young stellar population in the modelling is important for explaining the observed stellar energy distribution. However, the discrepancy between the observed and modelled thermal emission at far-infrared wavelengths, the so-called dust energy balance problem, is still present: the model underestimates the observed fluxes by a factor of about two. We compare two different dust models, and find that dust parameters and thus the spectral energy distribution in the infrared domain are sensitive to the adopted dust model. In general, the THEMIS model reproduces the observed emission in the infrared wavelength domain better than the popular Zubko et al. BARE-GR-S model. Our study of IC 2531 is a pilot case for detailed and uniform radiative transfer modelling of the entire HEROES sample, which will shed more light on the strength and origins of the dust energy balance problem.