A&A 434, 849-866 (2005)
DOI: 10.1051/0004-6361:20042157
The optical-to-radio spectral energy distributions of low-metallicity blue compact dwarf galaxies
L. Hunt1, S. Bianchi1 and R. Maiolino21 INAF - Istituto di Radioastronomia/Sez. Firenze, Largo Enrico Fermi, 5, 50125 Firenze, Italy
e-mail: [hunt;sbianchi]@arcetri.astro.it
2 INAF - Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi, 5, 50125, Firenze, Italy
e-mail: maiolino@arcetri.astro.it
(Received 11 October 2004 / Accepted 3 January 2005 )
Abstract
We present global spectral energy distributions (SEDs) from 0.3
m to 90 cm
for a sample of seven low-metallicity blue compact dwarf galaxies (BCDs).
In addition to data compiled from the literature, we report new SCUBA data
for the galaxies in the sample, including the two most metal-poor star-forming galaxies known, I Zw 18 and SBS 0335-052. The standard starburst templates, M 82 and Arp 220, do not
give a good approximation to any of the BCD SEDs in our sample. Several SEDs are instead characterized by: (i) approximately flat radio spectra suggesting
dominant thermal processes; (ii) far-infrared (FIR) spectra which peak at or
shortward of 60
m; (iii) a significant warm dust component and absence of Aromatic Features in Emission (or PAHs) in the mid-infrared (MIR).
The SEDs of low-metallicity BCDs do not follow "canonical" scaling relations,
and the "standard" star-formation indicators based on radio continuum,
FIR, and MIR luminosities can be discrepant by factors of
10.
We present new models of the dust SEDs from 5
m to 1 cm, and derive
infrared luminosities, dust distributions, temperatures, and masses.
The observed SEDs and dust models are interpreted in terms of the active/passive regimes of
star formation and trends with metallicity. Finally, we discuss the
implications of our results on the
starburst populations which will
be detected by forthcoming submm and radio facilities.
Key words: galaxies: starburst -- galaxies: ISM -- ISM: dust, extinction -- galaxies: star clusters -- galaxies: evolution
SIMBAD Objects
© ESO 2005
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