Density correlations between solar wind and pick-up ions with New Horizons/SWAP near 11 AU

The Solar Wind Around Pluto (SWAP) instrument aboard the New Horizons spacecraft measured ion energy spectra of the solar wind and pick-up ions between 11 and 12 AU in late 2008. We report on detailed fitting of these spectra using an empirical model that includes major solar wind ions (H+, He2+, and O6+) as well as pick-up ions (from the interstellar and inner sources). We find a correlation between the densities of the solar wind H+ ions and all other populations. The two strongest correlations are with the interstellar pick-up ions and the inner source pick-up ions. These results could have implications for transport of pick-up ions through the heliosphere.