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| Main Authors: | , |
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| Format: | Preprint |
| Published: |
2025
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| Online Access: | https://arxiv.org/abs/2509.25886 |
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| _version_ | 1866915524585193472 |
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| author | Wu, Qi-Zuo Liu, Ruo-Yu |
| author_facet | Wu, Qi-Zuo Liu, Ruo-Yu |
| contents | 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_25886 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spatial distribution of secondary electrons' Synchrotron emission: property and implication Wu, Qi-Zuo Liu, Ruo-Yu High Energy Astrophysical Phenomena 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. |
| title | Spatial distribution of secondary electrons' Synchrotron emission: property and implication |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2509.25886 |