河外极高能宇宙线的起源

Abstract

The origin of ultrahigh energy cosmic rays is a long-standing puzzle. Studies on these energetic particles will not only reveal the most violent process in the universe, but also extend our understanding on particle physics at extremely high energies. Thanks to large cosmic ray experiments such as the Pierre Auger Observatory (PAO) and the Telescope Array (TA), a lot of progress has been made in the studies on cosmic rays with energy above 10 18 eV, including the discovery of flux suppression at the highest energy of the spectrum or the GZK cutoff, the possible anisotropy signal especially the correlation with extragalactic objects and their chemical compositions. In this paper, we firstly give a brief review on the detection technique of ultrahigh energy cosmic rays and recent results from PAO and TA. And then, various candidate sources of ultrahigh energy cosmic rays such as gamma-ray bursts, active galactic nuclei, intergalactic shocks are introduced, as well as some basic theories on particle acceleration mechanisms. Also, we discuss the interactions of ultrahigh energy cosmic rays with photon fields, matter and magnetic fields. Some constraints on candidate sources can be obtained through multi-messengers like high energy neutrinos and gamma rays generated in the propagation of the cosmic rays from distant universe. Additionally, the possible anisotropy signal of ultrahigh energy cosmic ray events can also be used to study the distance and metallicity of the candidate sources, and probe Galactic and extragalactic magnetic fields. particle astrophysics, ultrahigh energy cosmic rays, neutrino, gamma ray, magnetic field