On the Spectral Curvature of VHE Blazar 1ES 1011+496: Effect of Spatial Particle Diffusion

• Published in: The Astrophysical journal 2017-02, Vol.836 (1), p.83
• Main Authors: Sinha, Atreyee, Sahayanathan, S., Acharya, B. S., Anupama, G. C., Chitnis, V. R., Singh, B. B.
• Format: Article
• Language: English
• Subjects: Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BL LACERTAE OBJECTS; BL Lacertae objects: individual (1ES 1011+496); Broadband; Curvature; DIFFUSION; Diffusion effects; DISTRIBUTION; EMISSION; Emissions; ENERGY DEMAND; ENERGY DEPENDENCE; ENERGY SPECTRA; GALAXIES; galaxies: active; Particle diffusion; Photons; Power law; radiation mechanisms: non-thermal; Spectra; Spectral energy distribution; TELESCOPES; X RADIATION
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/836/1/83

A detailed multi-epoch study of the broadband spectral behavior of the very high energy (VHE) source 1ES 1011+496 provides us with valuable information regarding the underlying particle distribution. Simultaneous observations of the source at optical/UV/X-ray/γ-ray during three different epochs, as obtained from Swift-UVOT/Swift-XRT/Fermi-LAT, are supplemented with the information available from the VHE telescope array, HAGAR. The long-term flux variability at the Fermi-LAT energies is clearly found to be lognormal. It is seen that the broadband spectral energy distribution of 1ES 1011+496 can be successfully reproduced by synchrotron and synchrotron self Compton emission models. Notably, the observed curvature in the photon spectrum at X-ray energies demands a smooth transition of the underlying particle distribution from a simple power law to a power law with an exponential cutoff, or a smooth broken power law distribution, which may possibly arise when the escape of the particles from the main emission region is energy dependent. Specifically, if the particle escape rate is related to its energy as E 0.5 , then the observed photon spectrum is consistent with the ones observed during the various epochs.