Blue Compact Dwarf Galaxies with Spitzer: The Infrared/Radio Properties

TL;DR

This study examines the infrared and radio emission correlations in 28 blue compact dwarf galaxies, revealing that these low-luminosity galaxies follow the same far-infrared to radio correlation as larger star-forming galaxies, with some variations related to metallicity.

Contribution

It extends the known far-infrared to radio correlation to lower luminosity, low-metallicity dwarf galaxies observed by Spitzer, highlighting similarities and differences with larger star-forming galaxies.

Findings

BCD galaxies follow the same FIR-radio correlation as larger star-forming galaxies.

Mid-infrared to radio correlation in BCDs is similar to starburst galaxies, with larger dispersion.

No strong correlation between q parameter and metallicity or dust temperature, but hints of metallicity dependence.

Abstract

We study the correlation between the radio, mid-infrared and far-infrared properties for a sample of 28 blue compact dwarf (BCD) and low metallicity star-forming galaxies observed by Spitzer. We find that these sources extend the same far-infrared to radio correlation typical of star forming late type alaxies to lower luminosities. In BCDs, the 24um (or 22um) mid-infrared to radio correlation is similar to starburst galaxies, though there is somewhat larger dispersion in their q_24 parameter compared to their q_FIR. No strong correlations between the q parameter and galaxy metallicity or effective dust temperature have been detected, though there is a hint of decreasing q_24 at low metallicities. The two lowest metallicity dwarfs in our sample, IZw18 and SBS0335-052E, despite their similar chemical abundance, deviate from the average q$_{24}$ ratio in opposite manners, displaying an apparent radio excess and dust excess respectively.