Can Charge Exchange Explain Anomalous Soft X-Ray Emission in the Cygnus Loop?
Wu, Y.; Shelton, R. L.; Henley, D. B.; Cumbee, R. S.; Schultz, D. R.; Stancil, P. C.; Nolte, J. L.
United States, United Kingdom, China
Abstract
Recent X-ray studies have shown that supernova shock models are unable to satisfactorily explain X-ray emission in the rim of the Cygnus Loop. In an attempt to account for this "anomalously" enhanced X-ray flux, we fit the region with a model including theoretical charge exchange (CX) data along with shock and background X-ray models. The model includes the CX collisions of O8 +, O7 +, N7 +, N6 +, C6 +, and C5 + with H with an energy of 1 keV u-1 (438 km s-1). The observations reveal a strong emission feature near 0.7 keV that cannot fully be accounted for by a shock model, nor the current CX data. Inclusion of CX, specifically O7 + + H, does provide for a statistically significant improvement over a pure shock model.