Spontaneously quenched gamma-ray spectra from compact sources

Abstract

We study a mechanism for producing intrinsic broken power-law gamma-ray spectra in compact sources. This is based on the principles of automatic photon quenching, according to which, gamma-rays are being absorbed on spontaneously produced soft photons, whenever the injected luminosity in gamma-rays lies above a certain critical value. We derive an analytical expression for the critical gamma-ray compactness in the case of power-law injection. For the case where automatic photon quenching is relevant, we calculate analytically the emergent steady-state gamma-ray spectra. We perform also numerical calculations in order to back up our analytical results. We show that a spontaneously quenched power-law gamma-ray spectrum obtains a photon index 3Γ/2, where Γ is the photon index of the power-law at injection. Thus, large spectral breaks of the gamma-ray photon spectrum, e.g. $\Delta \Gamma \gtrsim 1$, can be obtained by this mechanism. We also discuss additional features of this mechanism that can be tested observationally. Finally, we fit the multiwavelength spectrum of a newly discovered blazar (PKS 0447-439) by using such parameters, as to explain the break in the gamma-ray spectrum by means of spontaneous photon quenching, under the assumption that its redshift lies in the range 0.1<z<0.24.

14 pages, 9 figures, 2 tables, accepted for publication in A&A

References in corpus (9)

• Fermi Large Area Telescope Bright Gamma-ray Source List
• Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey
• MAGIC discovery of VHE Emission from the FSRQ PKS 1222+21
• New constraints on the Mid-IR EBL from the HESS discovery of VHE gamma rays from 1ES 0229+200
• Formation of hard VHE gamma-ray spectra of blazars due to internal photon-photon absorption
• Discovery of VHE gamma-rays from the blazar 1ES 1215+303 with the MAGIC Telescopes and simultaneous multi-wavelength observations
• Active Galactic Nuclei under the scrutiny of CTA
• Discovery of TeV gamma-ray emission from PKS 0447-439 and derivation of an upper limit on its redshift
• On proton synchrotron blazar models: the case of quasar 3C 279

Cited by in corpus (4)

• Bethe-Heitler emission in BL Lacs: filling the gap between X-rays and $\gamma$-rays
• A self-consistent and time-dependent hybrid blazar emission model - Properties and application
• Constraints of Flat Spectrum Radio Quasars in the hadronic model: the case of 3C 273
• A roadmap to hadronic supercriticalities: a comprehensive study of the parameter space for high-energy astrophysical sources