Observations of the blazar PKS 2023-07 in flaring state with H.E.S.S. And Fermi-LAT in 2016-2017 and constraints on an intrinsic cut-off
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Date
2019Author
Emery, G.
Zacharias, M.
Jankowsky, F.
Lenain, J.-P.
Marais, J.P.
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PKS 2023−07 is a flat spectrum radio quasar located at a redshift z = 1.388, farther than any
source currently detected at very high energies (E > 100 GeV). At such energies, absorption by
the extragalactic background light (EBL) renders the detection of distant sources particularly
challenging. The High Energy Stereoscopic System (H.E.S.S.) observed the source following reports from AGILE (April 2016) and Fermi-LAT (April 2016, September and October 2017) on
high-flux states in gamma rays. During each of the three flaring periods, near-simultaneous observations were obtained with H.E.S.S., Fermi-LAT and multiple telescopes at other wavelengths.
Though the source was not significantly detected by H.E.S.S., upper limits were derived for each
observation period. Through constraints given by Fermi-LAT in the MeV–GeV domain and differential upper limits by H.E.S.S., we searched for an intrinsic cutoff in the EBL-corrected gamma
ray spectrum of PKS 2023−07