Spatial distribution of secondary electrons' Synchrotron emission: property and implication
Year: 2025
Type: preprint
Abstract: Galactic $γ$-ray sources can be produced by either high-energy protons via proton-proton collisions or electrons/positrons via inverse Compton scattering. Distinguishing between the hadronic and leptonic origin of $γ$-ray emission in Galactic sources remains challenging. Measurements of non-thermal X-ray spectra of these sources, which could originate from primary electrons in the leptonic scenario or secondary electrons/positrons in the hadronic scenario, have been suggested as an efficient way of discriminating between these scenarios. In this work, we investigate the morphology of the X-ray emission from secondary electrons/positrons. By calculating the surface brightness profile and the photon index profile of X-ray emission, we find that secondary electrons produce a distinctively flat X-ray surface brightness profile. Our results suggest that, in addition to the X-ray spectrum, the X-ray morphology is crucial to determine the radiation mechanism of ultrahigh-energy $γ$-ray sources and help to identify sources of PeV cosmic rays.
Source: arXiv (Cornell University)
Authors: Wu, Qi-Zuo, Liu, Ruo-Yu
Institution: Nanjing University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G6625960585, G8155336024
OpenAlex ID: W7084447492
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