TRACING THE SOURCES OF COSMIC RAYS WITH MOLECULAR IONS

The rate of ionization by cosmic rays (CRs) in interstellar gas directly associated with gamma-ray-emitting supernova remnants (SNRs) is for the first time calculated to be several orders of magnitude larger than the Galactic average. Analysis of ionization-induced chemistry yields the first quantitative prediction of the astrophysical H-2(+) emission line spectrum, which should be detectable together with H-3(+) lines. The predicted coincident observation of those emission lines and gamma-rays will help prove that SNRs are sources of CRs.