Leptonic and hadronic modeling of Fermi-LAT hard spectrum quasars and predictions for high-energy polarization
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Date
2018Author
Paliya, Vaidehi S.
Böttcher, Markus
Zhang, Haocheng
Ajello, M.
Domínguez, A.
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We present the results of a study of the time-averaged spectral energy distributions (SEDs) of eight flat spectrum
radio quasars (FSRQs) present in the second catalog of high energy sources detected beyond 50 GeV by the Fermi
Large Area Telescope (2FHL). Both leptonic and hadronic scenarios are adopted to explain the multiwavelength
SEDs and we find them to be marginally consistent with the 2FHL spectra above 50 GeV. We derive the expected
degree of X-ray and γ-ray polarizations both for the average and elevated activity states and note that (i) a hadronic
radiative model consistently predicts a higher degree of high energy polarization compared to leptonic ones and (ii)
the X-ray polarization degree is higher than the γ-ray polarization in the leptonic scenario, but similar to the γ-ray
polarization if the observed radiation is powered by hadronic processes. From the leptonic modeling, the location
of the γ-ray emitting region is found to be at the outer edge of the broad line region (BLR) and is consistent with
the γγopacity estimates for the γ-ray absorption by the BLR. We conclude that a majority of the FSRQs could be
detected by the upcoming Cherenkov Telescope Array, though future high energy polarimeters will be able to
detect them only during elevated activity states, which could provide supportive evidence for the hadronic origin of
the X-ray and γ-ray emission
URI
http://hdl.handle.net/10394/30845https://doi.org/10.3847/1538-4357/aad1f0
http://iopscience.iop.org/article/10.3847/1538-4357/aad1f0/pdf