Origin of gamma-ray emission in the shell of Cassiopeia A
| Autor: | Saha, L., Ergin, T., Majumdar, P., Bozkurt, M., Ercan, E. N. |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | A&A, Volume 563, A88 (2014) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/201323218 |
| Popis: | Non-thermal X-ray emission from the shell of Cassiopeia A (Cas A) has been an interesting subject of study, as it provides information about relativistic electrons and their acceleration mechanisms in the shocks. Chandra X-ray observatory revealed the detailed spectral and spatial structure of this SNR in X-rays. The spectral analysis of Chandra X-ray data of Cas A shows unequal flux levels for different regions of the shell, which can be attributed to different magnetic fields in those regions. Additionally, the GeV gamma-ray emission observed by Large Area Telescope on board Fermi Gamma Ray Space Telescope showed that the hadronic processes are dominating in Cas A, a clear signature of acceleration of protons. In this paper we aim to explain the GeV-TeV gamma-ray data in the context of both leptonic and hadronic scenario. We modeled the multi-wavelength spectrum of Cas A. We use synchrotron emission process to explain the observed non-thermal X-ray fluxes from different regions of the shell. These result in estimation of the model parameters, which are then used to explain TeV gamma-ray emission spectrum. We also use hadronic scenario to explain both GeV and TeV fluxes simultaneously. We show that a leptonic model alone cannot explain the GeV-TeV data. Therefore, we need to invoke a hadronic model to explain the observed GeV-TeV fluxes. We found that although pure hadronic model is able to explain the GeV-TeV data, a lepto-hadronic model provides the best fit to the data. Comment: Accepted in A&A |
| Databáze: | arXiv |
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