Search for PeVatrons in Milky-way Galaxy by Cosmic Gamma-ray Observations
Cosmic rays are among long standing mysteries of the Universe since the origin and the acceleration mechanism of cosmic rays are not known well. In our Milky-way galaxy, it is expected that there are cosmic-ray accelerators, called PeVatrons, which can produce PeV cosmic rays. Gamma-ray observations are expected to play a prominent role in probing into mysteries of PeVatrons since gamma rays are produced by interaction of cosmic rays. In fact, the Fermi Gamma-ray Space Telescope found the first undeniable evidence of cosmic ray acceleration in supernova remnants (SNRs) in 2013. However, it is not yet conclusive whether the SNRs are PeVatrons or only PeVatrons in our galaxy. In this talk, recent progresses and future prospects on uncovering PeVatrons will be discussed.