Gamma-ray flare and absorption in the Crab nebula: lovely TeV–PeV astrophysics




We spectrally fit the GeV gamma-ray flares that have recently been observed in the Crab nebula by considering a small blob Lorentz-boosted towards us. We point out that the corresponding inverse Compton flare at the TeV–PeV region is more enhanced than synchrotron emission by a Lorentz factor squared (∼Γ2). This already excludes math formula and it will be detected by future TeV–PeV observatories, such as the Cherenkov Telescope Array (CTA), the Tibet Air Shower plus Muon Detector (Tibet AS+MD) array and the Large High Altitude Air Shower Observatory (LHAASO), for math formula. We also show that PeV photons emitted from the Crab nebula are absorbed by cosmic microwave background radiation through electron–positron pair creation.