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Title: The cosmic-ray population of the galactic central molecular zone

The conditions in the Galactic Center are often compared with those in starburst systems, which contain higher supernova rates, stronger magnetic fields, more intense radiation fields, and larger amounts of dense molecular gas than in our own Galactic disk. Interactions between such an augmented interstellar medium and cosmic rays result in brighter radio and γ-ray emission. Here, we test how well the comparisons between the Galactic Center and starburst galaxies hold by applying a model for cosmic-ray interactions to the Galactic Center to predict the resulting γ-ray emission. The model only partially explains the observed γ-ray and radio emission. The model for the γ-ray spectrum agrees with the data at TeV energies but not at GeV energies. Additionally, as the fits of the model to the radio and γ-ray spectra require significant differences in the optimal wind speed and magnetic field strength, we find that the single-zone model alone cannot account for the observed emission from the Galactic Center. Our model is improved by including a soft, additional cosmic-ray population. We assess such a cosmic-ray population and its potential sources and find that a cosmic-ray electron spectrum is energetically favored over a cosmic-ray proton spectrum.
Authors:
;  [1] ;  [2]
  1. Department of Physics, University of Wisconsin-Madison, Madison, WI (United States)
  2. Department of Astronomy, University of Wisconsin-Madison, WI (United States)
Publication Date:
OSTI Identifier:
22365539
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 790; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC RADIATION; ELECTRON SPECTRA; EMISSION; GALAXIES; GALAXY NUCLEI; GAMMA RADIATION; GEV RANGE; MAGNETIC FIELDS; PROTON SPECTRA; STELLAR WINDS; TEV RANGE; VELOCITY