enhanced in N [@willingale_etal03; @miller_etal08; @ursino_etal16]. These measurements alone do not constrain the NPS distance, which makes it unclear whether the enhancement is associated with the Fermi bubbles.

Several independent methods place constraints on the NPS distance, but there is tension between the results. @sofue15 analyzed how the NPS X-ray emission varies with extinction near the Aquila Rift, and concluded that the NPS must be behind the rift and $>$1 kpc from the Sun. @puspitarini_etal14 compared three-dimensional models of the Milky Way’s ISM and found no evidence for a low-density, hot cavity capable of producing the NPS X-ray emission within $\approx$200 pc of the Sun. Alternatively, @sun_etal15 mapped the NPS in polarized radio emission and constrained the distance using maps of Faraday rotation measure and depth. They argue that the NPS emission at $b \gtrsim$50 is likely within a few hundred parsecs of the Sun, while emission at lower latitudes can be either local or distant depending on the sign of the Milky Way’s large-scale magnetic field.

These distance discrepancies are problematic because the NPS could be a region of compressed circumgalactic medium (CGM) material due to the Fermi bubbles’ expansion, and thus a probe of their kinematics. This scenario 