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Bender
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Ultra-Long-Wavelength Morphology of Loop I/NPS as an Origin Discriminant
Phenomenological emissivity models that predict how the Loop I / North Polar Spur giant radio arc appears below ~30 MHz under its two competing origin scenarios — a complex of nearby supernova remnants versus a giant bubble near the Galactic Center — showing that free-free absorption by interstellar electrons makes the low-latitude arc vanish below ~3 MHz only in the Galactic-Center case, giving upcoming space missions (DSL, FARSIDE) an observational test of its origin.