Chandra's First Decade of Discovery


Evidence for Solar Wind Charge Exchange Emission Towards the Chandra Deep Field North

Jonathan Slavin, Harvard-Smithsonian Center for Astrophysics
Bradford J. Wargelin (CfA), Ryan Hickox (CfA), Ina Robertson (U of Kansas)

Soft X-ray emission from within the heliosphere is now recognized as a major source of contamination in observations of emission from hot gas in the Local Bubble and can also be significant in observations of faint extended galactic and extragalactic sources such as supernova remnants and clusters. This emission is generated by charge exchange between highly ionized solar wind ions and inflowing neutral H and He from the Local Interstellar Cloud, which immediately surrounds the Solar System. The Solar Wind Charge Exchange (SWCX) emission is expected to be enhanced in the direction downwind of the Sun where neutral He is focused by the Sun's gravity (the helium focusing cone).We present results of an analysis of observations toward the Chandra/Hubble Deep Field North in which we attempt to detect SWCX emission by comparing data collected while looking through the helium focusing cone with those collected looking away from the cone. After careful flare filtering and source exclusion we compare the spectra with particular attention to the possible presence of lines from OVII and OVIII. We compare our results with models for the expected emission and present the implications for the heliosphere and emission from the Local Bubble.

Solar Wind Charge Exchange in the Chandra Deep Field-South During Solar Max and Min

Bradford J. Wargelin, SAO
Jonathan D. Slavin (SAO), Ina P. Robertson (U. Kansas), Michael Juda (SAO)

Uniquely among X-ray deep field observations, the Chandra Deep Field-South contains data collected both during Solar Maximum (1999 and 2000) and during Solar Minimum (2007). These 2 Ms of data also sample lines of sight through and to the side of the solar helium focusing cone. When combined with data on solar wind composition from the ACE satellite, these observations permit studies of the effects of solar wind variability and viewing geometry (through the heliosphere and geocorona) on SWCX emission, and strongly constrain the level of hot-gas emission from the Local Bubble.