The electromagnetic radiation associated with the energy dissipated by cosmic rays in interstellar hydrogen

Abstract

Evidence is presented for an interstellar cosmic-ray spectrum that arises from a source function which is a power law in kinetic energy per nucleon (αE−2.5) and which gets modified by the energy degradation of particles that traverse an average of 3–6 g/cm2 of interstellar matter, with paths distributed according to a steady-state model (Cowsik et al. 1966).For the interstellar spectrum inferred, the Coulomb interactions of cosmic rays with the hydrogen atoms of HI clouds are found to supply the correct energy input for maintaining at equilibrium the observed gas temperature of 102 °K. These interactions give rise to a high electron concentration (~10−1 cm−3), consistent with observations. The galactic backgrounds of X rays and Hα radiation are shown to be measures of the electromagnetic interactions of cosmic rays with the hydrogen atoms of HI clouds.