The optical-to-radio spectral energy distributions of low-metallicity blue compact dwarf galaxies

Free access article

Issue		A&A Volume 434, Number 3, May II 2005


Page(s)		849 - 866
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20042157

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

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.