A Few Selected Topics in Extreme Astrophysical Phenomena: Gamma-ray Burst as a Source of Multi-messenger Astrophysics and Cosmic Particles as a Would-be Messenger

Abstract

These days of astrophysics are full of exciting discoveries. Gravitational waves are directly found for the first time by Laser Interferometer Gravitational-wave Observatory. Merging of compact astrophysical objects (neutron star and neutron star) is detected via multi-messengers of gravitational wave and all wavelengths of photons for the first time by worldwide observatories on ground and in space. Interesting unknowns of the gamma-ray sky are introduced by Fermi, and many details of gamma-ray bursts (GRBs) become unveiled by the Swift space mission and ground based observatories. Astrophysical neutrinos with the highest energy are detected by the IceCube telescope. Hot and Warm sports, anisotropy of ultra-high energy cosmic rays, are found by the Telescope Array and Pierre Auger observatories, respectively. The spectral break in cosmic rays around 200 GeV is discovered and verified for all elements of cosmic rays, which requires a completely different paradigm in cosmic ray propagation. Combining all of those information allows us to learn the structure and evolution of the universe including thermal and non-thermal astrophysical sources, their spatial distributions, time evolutions and properties. Here we overview a few topics particularly emphasizing GRBs, as sources of multi-messenger astrophysics, in connection to GWs, neutrinos, and cosmic rays. Finally we introduce our space experiments on GRBs and cosmic rays for those physics targets.