Studying the Interstellar Medium and the inner region of NPS/Loop 1 with shadow observations toward MBM36

TL;DR

This study uses shadow observations of MBM36 with Suzaku to disentangle local and distant X-ray emission components, revealing insights into the Galactic Bulge, NPS, and halo contributions.

Contribution

It provides a detailed spectral analysis of the soft X-ray background using shadow observations, identifying multiple thermal components and constraining their origins.

Findings

Identified two non-local thermal components at 0.12 keV and 0.29 keV.

Confirmed the NPS as a hypershell from the Galactic Center.

Ruled out a nearby bubble as the source of NPS emission.

Abstract

We analyzed data from a shadow observation of the high density molecular cloud MBM36 (l~4{\deg}, b~35{\deg}) with Suzaku. MBM36 is located in a region that emits relatively weakly in the 3/4~keV band, compared to the surrounding NPS/Loop 1 structure and the Galactic Bulge. The contrast between a high and low density targets in the MBM36 area allows one to separate the local and distant contributors to the Soft Diffuse X-ray Background, providing a much better characterization of the individual components compared to single pointing observations. We identify two non-local thermal components, one at kT~0.12 keV and one at kT~0.29keV. The colder component matches well with models of emission from the higher latitude region of the Galactic Bulge. The emission of the warmer component is in agreement with models predicting that the NPS is due to a hypershell from the center of the Milky Way. Geometrical and pressure calculations rule out a nearby bubble as responsible for the emission associate with the NPS. Any Galactic Halo/CircumGalactic Halo emission, if present, is outshined by the other components. We also report an excess emission around 0.9~keV, likely due to an overabundance of NeIX.