EDP Sciences
Free Access
Issue
A&A
Volume 434, Number 3, May II 2005
Page(s) 849 - 866
Section Extragalactic astronomy
DOI https://doi.org/10.1051/0004-6361:20042157
Published online 18 April 2005


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. Maiolino2

1  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 $\mu$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 $\mu$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 $\ga$10. We present new models of the dust SEDs from 5 $\mu$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 $z\ga6$ 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

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.