Ultimate synchrotron cutoff in gamma-ray spectra of blazars as a signature of the converter mechanism

Abstract

There is a robust upper limit on the energy of synchrotron radiation in high-energy astrophysics: $\sim m_{\mathrm{e}}{c}^2/\alpha$, where $\alpha =1/137$ is the fine structure constant and the value refers to the comoving frame of the fluid. This is the maximal energy of synchrotron photons which can be emitted by an electron having an arbitrarily high initial energy after it turns by angle $\sim \pi$ in the magnetic field. This upper limit can be naturally reached if the converter mechanism contributes to the jet radiation and can be imprinted in spectra of some blazars as a cutoff or a dip in the GeV range. We use numerical simulations to probe the range of parameters of a radiating jet where the ultimate synchrotron cutoff appears. We reproduce the variety of spectra depending on the source luminosity and on the scale of the emission site. We also compare our results with the EGRET blazar spectra in order to illustrate that agreement is possible but still not statistically significant. The predicted feature, if it exists, should be observed by {\it Fermi} in spectra of some blazars.

Accepted to MNRAS

References in corpus (5)

• Discovery of very high energy gamma-ray emission from the low-frequency peaked BL Lacertae object BL Lacertae
• Radiation from relativistic jets in blazars and the efficient dissipation of their bulk energy via photon breeding
• A photon breeding mechanism for the high-energy emission of relativistic jets
• Discovery of very high energy gamma-rays from the flat spectrum radio quasar 3C 279 with the MAGIC telescope
• Cosmic ray acceleration at relativistic shocks, shear layers, .