Gamma-ray flare and absorption in Crab Nebula: Lovely TeV-PeV   astrophysics
  We spectrally fit the GeV gamma-ray flares recently-observed in the Crab Nebula by considering a small blob Lorentz-boosted towards us. We point out that the corresponding inverse-Compton flare at TeV--PeV region is more enhanced than synchrotron by a Lorentz factor square \sim \Gamma^2, which is already excluding \Gamma \gtrsim 200 and will be detected by future TeV - PeV observatories, CTA, Tibet AS + MD and LHAASO for \Gamma \gtrsim 30. We also show that PeV photons emitted from the Crab Nebula are absorbed by Cosmic Microwave Background radiation through electron-positron pair creation. 
Kazunori Kohri, Yutaka Ohira, Kunihito Ioka
astro-ph.HE astro-ph.CO hep-ph