{
  "id": "2405.09612",
  "version": "v1",
  "published": "2024-05-15T18:00:01.000Z",
  "updated": "2024-05-15T18:00:01.000Z",
  "title": "Imprint of 'local opacity' effect in gamma-ray spectrum of blazar jet",
  "authors": [
    "Sushmita Agarwal",
    "Amit Shukla",
    "Karl Mannheim",
    "Bhargav Vaidya",
    "Biswajit Banerjee"
  ],
  "comment": "10 pages, 3 figures, 1 table, accepted for publication in ApJL",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Relativistic jets from accreting supermassive black holes at cosmological distances can be powerful emitters of $\\gamma$-rays. However, the precise mechanisms and locations responsible for the dissipation of energy within these jets, leading to observable $\\gamma$-ray radiation, remain elusive. We detect evidence for an intrinsic absorption feature in the $\\gamma$-ray spectrum at energies exceeding $10\\,$GeV, presumably due to the photon-photon pair production of $\\gamma$-rays with low ionization lines at the outer edge of Broad-line region (BLR), during the high-flux state of the flat-spectrum radio quasar PKS 1424$-$418. The feature can be discriminated from the turnover at higher energies resulting from $\\gamma$-ray absorption in the extragalactic background light. It is absent in the low-flux states supporting the interpretation that powerful dissipation events within or at the edge of the BLR evolve into fainter $\\gamma$-ray emitting zones outside the BLR, possibly associated with the moving VLBI radio knots. The inferred location of $\\gamma$-ray emission zone is consistent with the observed variability time scale of the brightest flare, provided that the flare is attributed to external Compton scattering with BLR photons.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-05-15T18:00:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "gamma-ray spectrum",
      "local opacity",
      "blazar jet",
      "flat-spectrum radio quasar pks",
      "moving vlbi radio knots"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}