Where in the Milky Way is the North Polar Spur?
Abstract
The true nature of the North Polar Spur (NPS) is obscured by our lack of information about its distance. It has been variously modeled as a nearby superbubble and the nuclear outflow from the Galaxy. Although the feature extends from the Galactic plane to b=85, and different parts may be at different distances, recent attention has focused on the base of the NPS and a possible connection to the Fermi bubbles. We have acquired a continuous mosiac of XMM observations covering the southern end of the NPS in order to determine whether the emission is absorption bounded or emission bounded. Our initial result is that the emission is absorption bounded and the bulk of the emission is must be further away than 300 pc. We present here a more subtle analysis of the same data, using new ESAS tools, to determine how much of the emission might be local.