Seminar:- Multiwavelength studies of G298.6-0.0: Possibly one of the oldest GeV supernova remnants

Hadronic Gamma-ray sources associated with supernova remnants(SNRs) can serve as stopwatches for the escape of cosmic rays from SNRs, which gradually develops from highest-energy particles to lowest-energy particles with time. In this work, the speaker and his team analyze the 13.7yr Fermi-LAT data to investigate the Gamma-ray feature in/around the SNR G298.6-0.0 region. With Gamma-ray spatial analyses, they detect three point-like components. Among them, Src-NE is at the eastern SNR shell, and Src-NW is adjacent to the western edge of this SNR. Src-NE and Src-NW demonstrate spectral breaks at energies around/below 1.8 GeV, suggesting an old SNR age of >10kyr. We also look into the X-ray emission from the G298.6-0.0 region, with the Chandra-Advanced CCD Imaging Spectrometer(Chandra-ACIS) data. The team detected an extended keV source having a centrally filled structure inside the radio shell. The X-ray spectra are well fit by a model which assumes a collisional ionisation equilibrium of the thermal plasma, further supporting an old SNR age. Based on their analyses of the NAN‧TEN CO- and Australia Telescope Compact Array-Parkes(NANTEN CO- and ATCA-Parkes) H I-line data, they determined a kinematic distance of ~10.1kpc from us to G298.6-0.0. This distance entails a large physical radius of the SNR of ~15.5pc, which is an additional evidence for an old age of >10kyr. Besides, the CO data cube enables us to three-dimensionally locate the molecular clouds which are potentially interacting with SNR G298.6-0.0 and could account for the hadronic Gamma-rays detected at Src-NE or Src-NW. Furthermore, the multiwavelength observational properties unanimously imply that the SNR-molecular cloud interaction occurs mainly in the northeast direction.

時間:2022.11.09(三) 15:30
地點:香港大學 莊月明物理樓522室
頻道:Zoom ID: 959-1277-5600 ← 25600
講者:Dr. Paul K. H. YEUNG(東京大學)