Host: Kohta Murase
1:30 PM
2:30 PM
HEP Seminar
The origin of ultrahigh-energy cosmic rays (UHECRs) (> 1 EeV) is a longstanding unresolved mysterious in modern astrophysics. UHECRs are related to the extreme high-energy astrophysical phenomena, and their secondary neutrinos and gamma-rays are important messengers of the universe. The composition of UHECRs is the key for us to understand their origin. Recent results from Pierre Auger Observatory have shown that the composition of UHECRs is not proton dominated, but show a trend towards heavier nuclei with increasing energy. According to the standard stellar evolution model, the inner core of massive stars or compact stars (including white dwarfs or the atmosphere of neutron stars) are rich in heavy nuclei. In this work, we study the origin of UHECRs from related candidate sources, including tidal disruption events (TDEs), low-luminosity gamma-ray bursts (LL GRBs), and engine-driven supernovae, where we aim to constrain the composition of UHECRs emitted from these sources considering progenitor dependencies. We also study the acceleration, survival, and propagation processes of UHECRs, and compare to observation results.