A spectral study of gamma-ray emitting active galactic nuclei

M. Pohl, R.C. Hartman, B.B. Jones, P. Sreekumar

Research output: Contribution to journalJournal articleResearchpeer-review


In this paper we present a statistical analysis of the gamma-ray spectra of flat-spectrum radio quasars (FSRQ) compared to those of BL Lacs. The average spectra and possible systematic deviations from power-law behaviour are investigated by summing up the intensity and the power-law fit statistic for both classes of objects. We also compare the time-averaged spectrum to that at the time of gamma-ray outbursts.

The spectrum of the average AGN is softer than that of the extragalactic gamma-ray background. It may be that BL Lacs, which on average have a harder spectrum than FSRQs, make up the bulk of the extragalactic background.

We also find apparent cut-offs at both low and high energies in the spectra of FSRQs at the time of gamma-ray outbursts. While the cut-off at high energies may have something to do with opacity, the cut-off at low energies may be taken as indication that the gamma-ray emission of FSRQs is not a one component spectrum.
Original languageEnglish
JournalAstronomy & Astrophysics
Issue number1
Pages (from-to)51-58
Publication statusPublished - 1997

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