ROLE OF LINE-OF-SIGHT COSMIC-RAY INTERACTIONS IN FORMING THE SPECTRA OF DISTANT BLAZARS IN TeV GAMMA RAYS AND HIGH-ENERGY NEUTRINOS

By Warren Essey, O. Kalashev, A. Kusenko, J. Beacom. 2010

138 citations recorded by the source corpus.

Active galactic nuclei (AGNs) can produce both gamma rays and cosmic rays. The observed high-energy gamma-ray signals from distant blazars may be dominated by secondary gamma rays produced along the line of sight by the interactions of cosmic-ray protons with background photons. This explains the surprisingly low attenuation observed for distant blazars, because the production of secondary gamma rays occurs, on average, much closer to Earth than the distance to the source. Thus, the observed spectrum in the TeV range does not depend on the intrinsic gamma-ray spectrum, while it depends on the output of the source in cosmic rays. We apply this hypothesis to a number of sources and, in every case, we obtain an excellent fit, strengthening the interpretation of the observed spectra as being due to secondary gamma rays. We explore the ramifications of this interpretation for limits on the extragalactic background light and for the production of cosmic rays in AGNs. We also make predictions for the neutrino signals, which can help probe the acceleration of cosmic rays in AGNs.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/27820b81d433f8215f7371b4d7b3cd8faf13cd00

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Citations in the corpus

Indications for a pair-production anomaly from the propagation of VHE gamma-rays (2012, background): “[3, 4] for gamma-ray induced cascades and [5–7] for ultra-high energy proton induced cascades)1.”
THE COSMIC CORE-COLLAPSE SUPERNOVA RATE DOES NOT MATCH THE MASSIVE-STAR FORMATION RATE (2011, background): “If secondary gamma rays produced en route by beamed cosmic rays are important (Essey & Kusenko 2010; Essey et al. 2011), the EBL could be even higher.”
Blazar Flares as an Origin of High-energy Cosmic Neutrinos? (2018, background): “The γ-ray signatures produced by CR-induced neutral beams were previously studied in Murase (2012) and Dermer et al. (2012) (see also Essey et al. 2010, 2011; Murase et al. 2012b, for related discussion about intergalactic cascades).”
Cosmological Magnetic Fields: Their Generation, Evolution and Observation (2013, background): “This implies that the UHECR cascade scenario for the VHE γ-ray emission works only if the IGMF strength is close to the lower bounds (Essey et al 2011a).”
BLAZARS AS ULTRA-HIGH-ENERGY COSMIC-RAY SOURCES: IMPLICATIONS FOR TeV GAMMA-RAY OBSERVATIONS (2011, background): “These cascade emissions may confuse interpretation of the minimum bulk Lorentz factor fromγγ opacity arguments and the level of the EBL (Essey & Kusenko 2010; Essey et al. 2010; Essey et al. 2011).”