This book presents two candidates for astrophysical accelerators of cosmic rays with petaelectron-volt (PeV) energies in our Galaxy, the so-called PeVatrons, through the observation of sub-PeV gamma rays performed by the Tibet air shower array. The two gamma-ray sources are TASG J1844-038—a newly detected source in this presented work—and HESS J1849-000. Reconstructing their gamma-ray energy spectra up to the sub-PeV range and also analyzing the archive data published by a radio survey, the book discusses in depth the emission mechanisms of the observed gamma rays and suggests that these two gamma-ray sources are candidates for PeVatrons. The results give insights into the population of PeVatron in the Galaxy, which is important to consider their contribution to the PeV cosmic rays observed at the Earth.
Introduction (introduction of the history of cosmic-ray physics and
sub-PeV gamma-ray astronomy to present the motivation of our study).- Tibet
air shower array and the muon detector array (explanation of the instrument
that we use).- Data analysis (explanation of the data analysis process).-
Result 1: Detection of a new gamma-ray source TASG J1844-038 in the HESS
J1843-033 region (results of the data analysis and the discussion).- Result
2: Observation of gamma rays from HESS J1849-000 (results of the data
analysis and the discussion).
Sei Kato is an ICRR fellow at the Institute for Cosmic Ray Research at the University of Tokyo. His work is concerned with the calibration of the ALPAQUITA detectors which started the data acquisition in September 2022 and continues the analysis of the data obtained by the Tibet air shower array. He received his master of science and Ph.D. from the University of Tokyo in 2020 and 2023, respectively.
Reconstructing the gamma-ray energy spectra of two gamma-ray sources, TASG J1844-038 and HESS J1849-000, up to the sub-PeV rfange in combination with the analysis of the published CO line emission data, he discussed in detail the origins of the observed gamma rays and suggested that these two gamma-ray sources are candidates for Galactic PeVatrons.
He was honored with the School of Science Encouragement Award of the University of Tokyo in 2023 and the Student Presentation Award of the Physical Society of Japan in 2020, 2023.
