Gamma-ray flare and absorption in Crab Nebula: Lovely TeV-PeV astrophysics

TL;DR

This paper models gamma-ray flares in the Crab Nebula using a Lorentz-boosted small blob, predicting enhanced inverse-Compton emission at TeV-PeV energies and discussing photon absorption by the CMB, with implications for future observatories.

Contribution

It introduces a Lorentz-boosted blob model to explain gamma-ray flares and predicts observable TeV-PeV signatures and photon absorption effects.

Findings

Inverse-Compton flare is more enhanced than synchrotron by \, \\Gamma^2.

Future observatories can detect flares for \, \\Gamma 30.

PeV photons are absorbed by CMB via pair creation.

Abstract

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.