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The diagnostic power of radio spectra from star-forming galaxies

Published online by Cambridge University Press:  10 June 2020

Eric J. Murphy Open the ORCID record for Eric J. Murphy [Opens in a new window]
Eric J. Murphy*
Affiliation:
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22901, U.S.A. email: emurphy@nrao.edu
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Abstract

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Radio continuum emission from galaxies is powered by a combination of distinct physical processes, each providing unique diagnostic information. Over frequencies spanning ∼ 1–120 GHz, radio spectra of star-forming galaxies are primarily comprised of: (1) non-thermal synchrotron emission powered by accelerated cosmic-ray electrons/positrons; (2) free-free emission from young massive star-forming (H ii) regions; (3) anomalous microwave emission, which is a dominant, but completely unconstrained, foreground in cosmic microwave background experiments; and (4) cold, thermal dust emission that accounts for most of the dust and total mass content in the interstellar medium in galaxies. In this proceeding, we discuss these key energetic processes that contribute to the radio emission from star-forming galaxies, with an emphasis on frequencies ≳30 GHz, where current investigations of star formation within nearby galaxies show that the free-free emission begins to dominate over non-thermal synchrotron emission. We also discuss how planned radio facilities that will access these frequencies, such as a next-generation Very Large Array (ngVLA), will be transformative to our understanding of the star formation process in galaxies.

Keywords

Star FormationRadio Continuum
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 15 , Symposium S341: Challenges in Panchromatic Modelling with Next Generation Facilities , November 2019 , pp. 177 - 186
Copyright
© International Astronomical Union 2020

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