X-rays from accelerated ion interactions

We have developed in detail the theory of X-ray line and continuum producti on due to atomic interactions of accelerated ions, incorporating in our cal culations information from a broad range of laboratory measurements. We app lied our calculations to the Orion region from which nuclear gamma-ray line observations with the COMPTEL instrument on the Compton Gamma Ray Observat ory (CGRO) were reported. The accelerated particles which produce this gamm a-ray emission via nuclear reactions also produce X-ray lines via atomic in teractions. We predict strong, relatively broad line emission in the range from 0.5 to 1 keV, mainly due to de-excitations in fast O ions. Current ROS AT observations of Orion do not provide unambiguous signatures for X-ray pr oduction by accelerated ions. However, if future X-ray observations with hi gh spectral resolution would confirm the predicted X-rays, the combined ana lysis of the X-ray and gamma-ray data will set important constraints on the origin of the accelerated particles and their interaction model.