Philip Kaaret (ST12) is a coauthor on the paper, “Soft X-Ray Energy Spectra in the Wide-field Galactic Disk Area Revealed with HaloSat”, published in the Astrophysical Journal. The first author was Kazuki Ampuku, a student at Nagoya University, who completed the work during a visit to MSFC in the summer of 2023. HaloSat was the first CubeSat for astrophysics competitively funded by NASA’s Science Mission Directorate and completed a 2-year all sky survey of soft X-ray emission in 2018-2020.
The goal of the work that went into this paper was to understand the nature of the soft X-ray energy emission from the Galactic disk. The paper presents analysis of data from HaloSat observations for five fields in the Galactic disk located far away from the Galactic center (135° < l < 254°). The energy spectra for all five shown the presence of unresolved high-temperature plasma in the Galactic disk with temperatures of 0.8–1.0 keV and emission measures of (8–11)×10−4 cm−6 pc. This suggests that hot plasma is present across the whole Galactic disk. To determine the origin of the emission, we observed an XMM-Newton field contained within one of the HaloSat fields. The stacked spectra of the X-ray point-like sources and near-infrared-identified point sources such as stars in the XMM-Newton field show a spectral feature similar to the hot plasma emission. This suggests that the hot plasma may partly originate from point-like sources such as stars.
This is the thirteenth paper published in peer-reviewed journals with HaloSat results.
