{
  "id": "2108.12271",
  "version": "v1",
  "published": "2021-08-27T13:44:52.000Z",
  "updated": "2021-08-27T13:44:52.000Z",
  "title": "Electron-proton co-acceleration on relativistic shocks in extreme-TeV blazars",
  "authors": [
    "Andreas Zech",
    "Martin Lemoine"
  ],
  "comment": "18 pages, 15 figures; accepted for publication in A&A",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "The multi-wavelength emission from a newly identified population of `extreme-TeV' blazars, with Compton peak frequencies around 1 TeV, is difficult to interpret with standard one-zone emission models. Large values of the minimum electron Lorentz factor and quite low magnetisation values seem to be required. We propose a scenario where protons and electrons are co-accelerated on internal or recollimation shocks inside the relativistic jet. In this situation, energy is transferred from the protons to the electrons in the shock transition layer, leading naturally to a high minimum Lorentz factor for the latter. A low magnetisation favours the acceleration of particles in relativistic shocks. The shock co-acceleration scenario provides additional constraints on the set of parameters of a standard one-zone lepto-hadronic emission model, reducing its degeneracy. Values of the magnetic field strength of a few mG and minimum electron Lorentz factors of 10^3 to 10^4, required to provide a satisfactory description of the observed spectral energy distributions of extreme blazars, result here from first principles. While acceleration on a single standing shock is sufficient to reproduce the emission of most of the extreme-TeV sources we have examined, re-acceleration on a second shock appears needed for those objects with the hardest gamma-ray spectra. Emission from the accelerated proton population, with the same number density as the electrons but in a lower range of Lorentz factors, is strongly suppressed. Satisfactory self-consistent representations were found for the most prominent representatives of this new blazar class.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-08-27T13:44:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "relativistic shocks",
      "extreme-tev blazars",
      "electron-proton co-acceleration",
      "minimum electron lorentz factor",
      "standard one-zone lepto-hadronic emission model"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 18,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}