GeV BREAKS IN BLAZARS AS A RESULT OF GAMMA-RAY ABSORPTION WITHIN THE BROAD-LINE REGION

By J. Poutanen, B. Stern. 2010

177 citations recorded by the source corpus.

Spectra of the brightest blazars detected by the Fermi Gamma-ray Space Telescope Large Area Telescope cannot be described by a simple power-law model. A much better description is obtained with a broken power law, with the break energies of a few GeV. We show here that the sharpness and the position of the breaks can be well reproduced by absorption of γ-rays via photon–photon pair production on He ii Lyman recombination continuum and lines. This implies that the blazar zone lies inside the region of the highest ionization of the broad-line region (BLR) within a light-year from a super-massive black hole. The observations of γ-ray spectral breaks open a way of studying the BLR photon field in the extreme-UV/soft X-rays, which are otherwise hidden from our view.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/96d7bf85d395bd49d743a4857f5fda70e1277cb0

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. F. Tavecchio
2. E. Orlando
3. Anna Franckowiak
4. A. Dom'inguez
5. J. Finke
6. L. Maraschi
7. G. Bonnoli
8. M. Sikora

In Nuclear and High Energy Physics

1. F. Tavecchio
2. E. Orlando
3. Anna Franckowiak
4. I. Grenier
5. G. Bonnoli
6. J. Finke
7. A. Dom'inguez
8. L. Maraschi

Citations in the corpus

• THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE (2015, background): “Several explanations have been proposed to account for this feature, including attenuation from He II line photons (Poutanen & Stern 2010), intrinsic electron spectral breaks (Abdo et al. 2009b), Lyα scattering (Ackermann et al. 2010), Klein-Nishina effects taking place when jet electrons scatter…”
• MINUTE-TIMESCALE >100 MeV γ-RAY VARIABILITY DURING THE GIANT OUTBURST OF QUASAR 3C 279 OBSERVED BY FERMI-LAT IN 2015 JUNE (2016, background): “…scales Rdiss ≪ rBLR, additional absorption may arise from the UV or soft X-ray radiation produced by the accretion disk or its corona (Dermer et al. 1992), radiation reprocessed by the surrounding medium (Blandford & Levinson 1995), or from high-ionization HeII lines (Poutanen & Stern 2010).”
• Detection of significant cm to sub-mm band radio and γ-ray correlated variability in Fermi bright blazars (2014, methodology): “…(ii) the high-energy spectral breaks observed by Fermi have been interpreted as γ-ray photo-absorption via He II Lyman recombination in the BLR (Poutanen & Stern 2010; Stern & Poutanen 2011), (iii) SED modeling can often describe well the high energy emission within leptonic scenarios by…”
• MAGIC DISCOVERY OF VERY HIGH ENERGY EMISSION FROM THE FSRQ PKS 1222+21 (2011, background): “4We note that this absorption has been invoked by Poutanen & Stern (2010) to explain the existence of an apparently “universal” break energy in the γ-ray spectrum of FSRQs at The energy above which the KN effects become important can be roughly expressed as: EKN ≃ 22.5 ν −1 o,15 GeV, where νo,15 is…”