Gamma-ray-loud blazars and beaming

Apr 1, 1995
13 pages
Published in:
  • Mon.Not.Roy.Astron.Soc. 273 (1995) 3, 583-595
  • Published: Apr 1, 1995

Citations per year

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Abstract: (Oxford University Press)
We study the entire sample of quasars detected above 100 MeV (by the EGRET instrument), on board CGRO. We find that the γ-ray luminosity correlates better with the radio luminosity than with the optical or X-ray luminosity, even if the different variability behaviour indicates different emission regions. A strong correlation is also found between the broad-band spectral indices α_ro, connecting the radio and the optical fluxes, and α_oγ, connecting the optical and the γ-ray fluxes. The γ-ray luminosity in BLLac objects is on average much less dominant than in the other sources. With the requirement that the γ-rays do not interact with X-rays (assumed cospatial) through photon-photon collisions, we calculate the lower limit on the Doppler or beaming factor of the γ-ray emission region for a large fraction of the sources of the sample, finding that relativistic motion is required in all cases.
  • radiation mechanisms: nonthermal
  • galaxies: active
  • BL Lacertae objects: general
  • quasars: general
  • gamma-rays: theory
  • X-rays: general
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