TY - JOUR
T1 - Variable gamma-ray emission induced by ultra-high energy neutral beams
T2 - Application to 4C +21.35
AU - Dermer, Charles D.
AU - Murase, Kohta
AU - Takami, Hajime
PY - 2012/8/20
Y1 - 2012/8/20
N2 - The flat-spectrum radio quasar 4C +21.35 (PKS 1222+216) displays prominent nuclear infrared emission from 1200K dust. A 70-400 GeV flare with10 minute variations during half an hour of observations was found by the MAGIC telescopes, and GeV variability was observed on sub-day timescales with the Large Area Telescope on Fermi. We examine 4C +21.35, assuming that it is a source of ultra-high energy cosmic rays (UHECRs). UHECR proton acceleration in the inner jet powers a neutral beam of neutrinos, neutrons, and γ-rays from pγ photopion production. The radiative efficiency and production spectra of neutrals formed through photohadronic processes with isotropic external target photons of the broad-line region (BLR) and torus are calculated. Secondary radiations made by this process have a beaming factor δ5 D, where δD is the Doppler factor. The pair-production optical depth for γ-rays and the photopion efficiency for UHECR neutrons as they pass through external isotropic radiation fields are calculated. If target photons come from the BLR and dust torus, large Doppler factors, δD ≳100, are required to produce rapidly variable secondary radiation with isotropic luminosity ≳10 47ergs-1 at the pc scale. The γ-ray spectra from leptonic secondaries are calculated from cascades initiated by the UHECR neutron beam at the pc-scale region and fit to the flaring spectrum of 4C +21.35. Detection of ≳100 TeV neutrinos from 4C +21.35 or other very high energy γ-ray blazars with IceCube or KM3NeT would confirm this scenario.
AB - The flat-spectrum radio quasar 4C +21.35 (PKS 1222+216) displays prominent nuclear infrared emission from 1200K dust. A 70-400 GeV flare with10 minute variations during half an hour of observations was found by the MAGIC telescopes, and GeV variability was observed on sub-day timescales with the Large Area Telescope on Fermi. We examine 4C +21.35, assuming that it is a source of ultra-high energy cosmic rays (UHECRs). UHECR proton acceleration in the inner jet powers a neutral beam of neutrinos, neutrons, and γ-rays from pγ photopion production. The radiative efficiency and production spectra of neutrals formed through photohadronic processes with isotropic external target photons of the broad-line region (BLR) and torus are calculated. Secondary radiations made by this process have a beaming factor δ5 D, where δD is the Doppler factor. The pair-production optical depth for γ-rays and the photopion efficiency for UHECR neutrons as they pass through external isotropic radiation fields are calculated. If target photons come from the BLR and dust torus, large Doppler factors, δD ≳100, are required to produce rapidly variable secondary radiation with isotropic luminosity ≳10 47ergs-1 at the pc scale. The γ-ray spectra from leptonic secondaries are calculated from cascades initiated by the UHECR neutron beam at the pc-scale region and fit to the flaring spectrum of 4C +21.35. Detection of ≳100 TeV neutrinos from 4C +21.35 or other very high energy γ-ray blazars with IceCube or KM3NeT would confirm this scenario.
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U2 - 10.1088/0004-637X/755/2/147
DO - 10.1088/0004-637X/755/2/147
M3 - Article
AN - SCOPUS:84864658271
SN - 0004-637X
VL - 755
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 147
ER -