Abstract
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, we analyze the 13.7 yr Fermi-LAT data to investigate the Gamma-ray feature in/around the SNR G298.6-0.0 region. With Gamma-ray spatial analyses, we 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 >10 kyr. We also look into the X-ray emission from the G298.6-0.0 region, with the Chandra-ACIS data. We 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 our analyses of the NANTEN CO- and ATCA-Parkes HI-line data, we determined a kinematic distance of ~10.1 kpc from us to G298.6-0.0. This distance entails a large physical radius of the SNR of ~15.5 pc, which is an additional evidence for an old age of >10 kyr. 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.
Biography
Paul K. H. Yeung graduated with a PhD degree from University of Hamburg, Germany. He has 8-year experience in High-Energy Astrophysics research. He is currently a postdoctoral research fellow in The University of Tokyo, Japan. He has been working on gamma-ray, X-ray and radio-line emissions of supernova remnant -- molecular cloud interaction systems.
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