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Abstract The extragalactic background light (EBL) contains all the radiation emitted by nuclear and accretion processes in stars and compact objects since the epoch of recombination. Measuring the EBL density directly is challenging, especially in the near-to-far-infrared wave band, mainly due to the zodiacal light foreground. Instead, gamma-ray astronomy offers the possibility to indirectly set limits on the EBL by studying the effects of gamma-ray absorption in the very high energy (VHE: >100 GeV) spectra of distant blazars. The High Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is one of the few instruments sensitive to gamma rays with energies abovemore »Free, publicly-accessible full text available July 1, 2023
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Abstract The High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory surveys the very high-energy sky in the 300 GeV to >100 TeV energy range. HAWC has detected two blazars above 11 σ , Markarian 421 (Mrk 421) and Markarian 501 (Mrk 501). The observations are comprised of data taken in the period between 2015 June and 2018 July, resulting in ∼1038 days of exposure. In this work, we report the time-averaged spectral analyses for both sources, above 0.5 TeV. Taking into account the flux attenuation due to the extragalactic background light, the intrinsic spectrum of Mrk 421 is described by amore »Free, publicly-accessible full text available April 1, 2023
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Free, publicly-accessible full text available January 1, 2023
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Free, publicly-accessible full text available January 1, 2023
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Free, publicly-accessible full text available January 1, 2023
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Free, publicly-accessible full text available January 1, 2023
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Free, publicly-accessible full text available January 1, 2023
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Free, publicly-accessible full text available January 1, 2023
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Free, publicly-accessible full text available January 1, 2023
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Free, publicly-accessible full text available January 1, 2023