Research Seminar:- Revealing the origins of GeV gamma-rays in the sky region containing Cl* 1806-20 & SNR G9.7-0.0
The massive stellar cluster Cl* 1806-20 and the SuperNova Remnant(SNR) G9.7-0.0 are potentially important sites of cosmic-ray acceleration. In this work, the speaker and his team analyze the 14.4 yr Fermi-LAT data to investigate the GeV gamma-ray feature in their sky region. With gamma-ray spatial analyses, they identify a number of components. Src-E is spatially coincident with the known TeV source HESS J1808-204 which is enclosing Cl* 1806-20. The 550 MeV Large Area Telescope(LAT) spectrum of Src-E is smoothly connected with the TeV spectrum of HESS J1808-204, without an indication of a turnover. This demonstrates a possible physical association between the GeV—TeV gamma-rays and the stellar cluster. Src-W is spatially coincident with an OH maser adjacent to SNR G9.7-0.0 (i.e. the orientation of SNR interaction with molecular clouds). The 0.3–20 GeV spectrum of Src-W follows a power-law with a soft photon index of ~2.9, suggesting an extremely old age of >30 kyr for SNR G9.7-0.0. Src-S is at the southeast of the SNR. Src-S demonstrates a “quasi-monoenergetic” spectrum with a sharp peak at ~2.8 GeV. For this, they propose a scenario where the secondary cosmic-ray nuclei escaping from the SNR interact with the circumstellar medium formed from the progenitor’s winds.
時間：2023.06.21(三) 11:30
地點：香港大學 莊月明物理樓522室
講者：Dr. Paul YEUNG K. H. (日本 東京大学)
語言：英語
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此活動由香港大學物理系主辦。
