Open AccessMassive star formation in galaxies: radiative transfer models of the UV to millimetre emission of starburst galaxies
Author(s) -
Efstathiou A.,
RowanRobinson M.,
Siebenmorgen R.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03269.x
Subject(s) - physics , astrophysics , radiative transfer , star formation , galaxy , millimeter , stellar population , stars , astronomy , molecular cloud , population , disc galaxy , luminous infrared galaxy , medicine , optics , environmental health
We present illustrative models for the UV to millimetre emission of starburst galaxies which are treated as an ensemble of optically thick giant molecular clouds (GMCs) centrally illuminated by recently formed stars. The models follow the evolution of the GMCs owing to the ionization‐induced expansion of the H ii regions and the evolution of the stellar population within the GMC according to the Bruzual & Charlot stellar population synthesis models. The effect of transiently heated dust grains/PAHs on the radiative transfer, as well as multiple scattering, is taken into account. The expansion of the H ii regions and the formation of a narrow neutral shell naturally explain why the emission from PAHs dominates over that from hot dust in the near‐ to mid‐infrared, an emerging characteristic of the infrared spectra of starburst galaxies. The models allow us to relate the observed properties of a galaxy to its age and star formation history. We find that exponentially decaying 10 7 –10 8 yr old bursts can explain the IRAS colours of starburst galaxies. The models are also shown to account satisfactorily for the multiwavelength data on the prototypical starburst galaxy M82 and NGC 6090, a starburst galaxy recently observed by ISO . In M82 we find evidence for two bursts separated by 10 7 yr. In NGC 6090 we find that at least part of the far‐infrared excess may be due to the age of the burst (6.4×10 7 yr). We also make predictions about the evolution of the luminosity of starbursts at different wavelengths which indicate that far‐infrared surveys may preferentially detect older starbursts than mid‐infrared surveys.