EAPSI: Understanding ion-atom collisions in our Galaxy

Cumbee Renata S, Athens GA

Investigators

Abstract

In order to improve our understanding of astrophysical objects in our galaxy, it is important to have models of the various processes that occur. Reliable models of X-ray emission due to a process called charge exchange (CX), a collision between an ion and a neutral atom or molecule, are currently of limited availability. Detailed knowledge of the emission spectra due to CX between ions and neutral hydrogen (H) and helium (He) are necessary to predict the resulting X-ray energy dependent spectra which we observe. This research will use explicit CX calculations produced by three astrophysically important collision systems. These calculations will then be benchmarked to measurements done by Dr. Hajime Tanuma's group at Tokyo Metropolitan University. Then, with collaborators at RIKEN, Osaka University, and Kyoto University, the calculated CX spectra will be compared to X-ray observations of the Cygnus Loop, a supernova remnant, using observations from the Japanese telescope Suzaku. This will give us insight into the processes occurring within the Cygnus Loop and other supernova remnants. This project will have a direct impact on advancing our understanding of atomic collisions and X-ray emission in various regions of our galaxy. CX is a fundamental process in atomic physics which has recently been attributed to the X-ray spectra of various astrophysical environments within our Solar System, supernova remnants, starburst galaxies, and extragalactic cooling flows. When both ions and neutrals are present, CX is one process that can occur which may dominate the ion emission spectra. This research will use explicit CX calculations produced by the astrophysically important collision systems of Fe{15+}, Fe{16+}, and Ne{8+} with He{+} to produce the X-ray emission spectra. This charge exchange data will then be used to model the Cygnus Loop, a supernova remnant that is currently not well understood in the X-ray regime. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.