Deep radio continuum imaging of the dwarf irregular galaxy IC 10: tracing star formation and magnetic fields

V. Heesen, U. Rau, M. P. Rupen, E. Brinks, D. A. Hunter

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23 Citations (Scopus)
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Abstract

We exploit the vastly increased sensitivity of the Expanded Very Large Array to study the radio continuum and polarization properties of the post-starburst, dwarf irregular galaxy IC 10 at 6 cm, at a linear resolution of similar to 50 pc. We find close agreement between radio continuum and Ha emission, from the brightest H II regions to the weaker emission in the disk. A quantitative analysis shows a strictly linear correlation, where the thermal component contributes 50% to the total radio emission, the remainder being due to a non-thermal component with a surprisingly steep radio spectral index of between -0.7 and -1.0 suggesting substantial radiation losses of the cosmic-ray electrons. We confirm and clearly resolve polarized emission at the 10%-20% level associated with a non-thermal superbubble, where the ordered magnetic field is possibly enhanced due to the compression of the expanding bubble. A fraction of the cosmic-ray electrons has likely escaped because the measured radio emission is a factor of three lower than what is suggested by the H alpha-inferred star formation rate.

Original languageEnglish
Article numberL23
Pages (from-to)-
Number of pages5
JournalAstrophysical Journal Letters
Volume739
Issue number1
DOIs
Publication statusPublished - 20 Sept 2011

Keywords

  • galaxies: dwarf
  • galaxies: individual (IC 10)
  • galaxies: magnetic fields
  • radio continuum: galaxies

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