Journal Article

Panchromatic radiative transfer modelling of stars and dust in the Sombrero galaxy

Ilse De Looze, Maarten Baes, Jacopo Fritz and Joris Verstappen

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 419, issue 1, pages 895-903
Published in print January 2012 | ISSN: 0035-8711
Published online December 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19759.x
Panchromatic radiative transfer modelling of stars and dust in the Sombrero galaxy

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We present a detailed study of the dust energy balance in the Sombrero galaxy M104. From a full radiative transfer analysis, including scattering, absorption and thermal re-emission, we construct models that can reproduce images at optical/near-infrared (near-IR) wavelengths, the observed stellar spectral energy distribution and the minor axis extinction profiles in the V and RC band. A standard model, which contains only an old stellar population to heat the dust, underestimates the observations of dust emission at IR wavelengths by a factor of ∼3. Supplementing this basic model with a young stellar component of low star formation activity in both the inner disc (star formation rate, SFR ∼0.21 M yr−1) and dust ring (SFR ∼0.05 M yr−1), we are capable of solving the discrepancy in the dust energy budget of the Sombrero galaxy at wavelengths shortwards of 100 μm. To account for the increased far-IR/submm emission beyond 100 μm, we propose an additional dust component distributed in quiescent clumps. This model with a clumpy dust structure predicts three-quarters of the total dust content (∼2.8 × 107 M) to reside in compact dust clouds with no associated embedded sources. Although the assumption of a clumpy dust structure in the Sombrero galaxy is supported by high-resolution optical data, we cannot rule out the possibility that dust grains with a higher dust emissivity account for part of the discrepancy in the energy budget at submm wavelengths.

Keywords: radiative transfer; dust, extinction; galaxies: individual: M104; galaxies: ISM; infrared: galaxies

Journal Article.  6494 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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