Lyman-α production by suprathermal protons |
| |
| Authors: | Joseph Silk Gary Steigman |
| |
| Institution: | (1) Princeton University Observatory, Princeton, USA;(2) Institute of Theoretical Astronomy, Cambridge, England;(3) Present address: Astronomy Department, University of California, Berkley;(4) Present address: Kellog Radiation Laboratory, California Institute of Technology, California, USA |
| |
| Abstract: | At sufficiently low energies, cosmic ray protons capture electrons from interstellar Hi and become neutral. In the subsequent cascade to the ground state a Doppler-shifted Ly- photon may be emitted. The neutral cosmic ray will be excited collisionally by further encounters with the ambient interstellar gas, emitting additional Doppler-shifted Ly- photons. We give the form of the cosmic ray spectrum down to 10 keV, assuming that there is no cosmic ray injection below 1 MeV. The neutral fraction is evaluated as a function of energy, and the diffuse ultraviolet flux is calculated. Comparison is made with observations in the range 1225–1340 Å. We conclude that far more stringent limits on the flux of subcosmic rays may be obtained by consideration of the heating and ionization of Hi regions. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
