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Please use this identifier to cite or link to this item: http://hdl.handle.net/10481/28313

Title: The dust SED of dwarf galaxies: I the case of NGC 4214
Authors: Hermelo, Israel
Lisenfeld, Ute
Relaño, Mónica
Tuffs, Richard J.
Popescu, Cristina C.
Groves, Brent
Issue Date: 2012
Abstract: Context. High-resolution data from Spitzer, Herschel, and Planck allow us to probe the entire spectral energy distribution (SED) of morphologically separated components of the dust emission from nearby galaxies and allow a more detailed comparison between data and models.
Aims. We wish to establish the physical origin of dust heating and emission based on radiation transfer models, that self-consistently connect the emission components from diffuse dust and the dust in massive star forming regions.
Methods. NGC 4214 is a nearby dwarf galaxy with a large set of ancillary data, ranging from the ultraviolet (UV) to radio, including maps from Spitzer and Herschel and detections from Planck. We mapped this galaxy with MAMBO at 1.2 mm at the IRAM 30 m telescope. We extracted separate dust emission components for the HII regions (plus their associated PDRs on pc scales) and for the diffuse dust (on kpc scales). We analysed the full UV to FIR/submm SED of the galaxy using a radiation transfer model that self-consistently treats the dust emission from diffuse and star forming (SF) complexes components, considering the illumination of diffuse dust both by the distributed stellar populations and by escaping light from the HII regions. While maintaining consistency within the framework of this model, we additionally used a model that provides a detailed description of the dust emission from the HII regions and their surrounding PDRs on pc scales. Thanks to the large amount of available data and many previous studies for NGC 4214, very few free parameters remained in the model fitting process.
Results. We achieve a satisfactory fit for the emission from HII + PDR regions on pc scales, with the exception of the emission at 8 μm, which is underpredicted by the model. For the diffuse emission we achieve a good fit if we assume that about 40–65% of the emission escaping the HII + PDR regions is able to leave the galaxy without passing through a diffuse ISM, which is not an unlikely scenario for a dwarf galaxy that has recently undergone a nuclear starburst. We determine a dust-to-gas mass ratio of 350–470, which is close to the expected value based on the metallicity.
Sponsorship: This work has been supported by the research projects AYA2007-67625-C02-02 and AYA2011-24728 from the Spanish Ministerio de Ciencia y Educación and the Junta de Andalucía (Spain) grants FQM108. I.H. was supported by a PhD grant from the Spanish Ministerio de Ciencia y Educación (BES-2008-008108). Part of this research has been supported by the ERG HER-SFR from the EC. This work is based on observations with the Instituto de Radioastronomía Milimétrica IRAM 30 m.
Publisher: EDP Sciences
Keywords: Dust
Extinction
Galaxies
NGC 4214
Dwarf
ISM
Star formation
URI: http://hdl.handle.net/10481/28313
ISSN: 0004-6361
1432-0746
Rights : Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License
Citation: Hermelo, I.; et al. The dust SED of dwarf galaxies: I the case of NGC 4214. Astronomy and Astrophysics, 549: A70 (2013). [http://hdl.handle.net/10481/28313]
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