CONSTRAINING THE FLUX OF LOW-ENERGY COSMIC RAYS ACCELERATED BY THE SUPERNOVA REMNANT IC 443
Blake, Geoffrey A.
Geballe, Thomas R.
McCall, Benjamin J.
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Publisher:Ohio State University
It has long been theorized that supernova remnants (SNR) accelerate the majority of Galactic cosmic rays. Observations in the $\gamma$-ray, X-ray, and radio regimes support this theory, at least for cosmic rays with energies above a few GeV. However, there is no direct evidence that SNRs accelerate cosmic rays in the MeV--GeV range. These low-energy cosmic rays are of great importance, as they are the primary means by which H$_2$ is ionized in the interstellar medium. Collisions between H$_2^+$ and H$_2$ will rapidly form H$_3^+$, a molecule which can then be observed to infer the ionization rate of H$_2$. Using the Subaru and Keck telescopes, we have searched for H$_3^+$ absorption in sight lines which probe molecular material known to be interacting with the SNR IC 443. By computing the ionization rate of H$_2$ in these sight lines, we constrain the flux of low-energy cosmic rays generated by this particular supernova remnant.
Author Institution: Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125; Max Planck Institute for Astronomy, Konigstuhl 17, Heidelberg D-69117, Germany; Subaru Telescope, Hilo, HI 96720; Gemini Observatory, Hilo, HI 96720; Department of Astronomy \& Astrophysics and Department of Chemistry, University of Chicago, Chicago, IL 60637; Departments of Chemistry and Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801