Diffuse Neutrino Intensity from the Inner Jets of Active Galactic Nuclei: Impacts of External Photon Fields and the Blazar Sequence

By Kohta Murase, Y. Inoue, C. Dermer. 2014

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We study high-energy neutrino production in inner jets of radio-loud active galactic nuclei (AGN), taking into account effects of external photon fields and the blazar sequence. We show that the resulting diffuse neutrino intensity is dominated by quasar-hosted blazars, in particular, flat spectrum radio quasars, and that PeV-EeV neutrino production due to photohadronic interactions with broadline and dust radiation is unavoidable if the AGN inner jets are ultrahigh-energy cosmic-ray (UHECR) sources. Their neutrino spectrum has a cutoff feature around PeV energies since target photons are due to Ly$\alpha$ emission. Because of infrared photons provided by the dust torus, neutrino spectra above PeV energies are too hard to be consistent with the IceCube data unless the proton spectral index is steeper than 2.5, or the maximum proton energy is $\lesssim100$ PeV. Thus, the simple model has difficulty in explaining the IceCube data. For the cumulative neutrino intensity from blazars to exceed $\sim{10}^{-8}~{\rm GeV}~{\rm cm}^{-2}~{\rm s}^{-1}~{\rm sr}^{-1}$, their local cosmic-ray energy generation rate would be $\sim10-100$ times larger than the local UHECR emissivity, but is comparable to the averaged gamma-ray blazar emissivity. Interestingly, future detectors such as the Askaryan Radio Array can detect $\sim0.1-1$ EeV neutrinos even in more conservative cases, allowing us to indirectly test the hypothesis that UHECRs are produced in the inner jets. We find that the diffuse neutrino intensity from radio-loud AGN is dominated by blazars with gamma-ray luminosity of $\gtrsim10^{48}~{\rm erg}~{\rm s}^{-1}$, and the arrival directions of their $\sim1-100$ PeV neutrinos correlate with the luminous blazars detected by Fermi.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/3f7e324b779b2abce9c5f2c5d0ecc5daa52ea580

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Citations in the corpus

OBSERVATION AND CHARACTERIZATION OF A COSMIC MUON NEUTRINO FLUX FROM THE NORTHERN HEMISPHERE USING SIX YEARS OF ICECUBE DATA (2016, background): “…2013; Kalashev et al. 2013; Laha et al. 2013; Razzaque 2013; Roulet et al. 2013; Stecker 2013; Anchordoqui et al. 2014; Gonzalez-Garcia et al. 2014; Murase et al. 2014; Tamborra et al. 2014; Bechtol et al. 2015; Senno et al. 2016) that have been proposed to explain the observed astrophysical…”
Star-forming galaxies as the origin of diffuse high-energy backgrounds: gamma-ray and neutrino connections, and implications for starburst history (2014, background): “Although the fraction of AGN associated with starbursts is highly uncertain, they are potentially important [53], and we here give quantitative estimates.”
IceCube-Gen2: the window to the extreme Universe (2020, background): “, [41, 42]).”
Blazar Flares as an Origin of High-energy Cosmic Neutrinos? (2018, background): “On the other hand, rapidly evolving sources such as FSRQs could give a significant contribution to the INB if neff0 ∼ n tot 0 ∼ 10 −9 Mpc−3.”
A Multimessenger Picture of the Flaring Blazar TXS 0506+056: Implications for High-energy Neutrino Emission and Cosmic-Ray Acceleration (2018, methodology): “We find a maximal all-flavor neutrino flux over 0.1 PeV 10 PeVe n of F 2 4 10max 12e » ´n e -n ( – ) ( ) erg cm−2 s−1.”
Leptohadronic single-zone models for the electromagnetic and neutrino emission of TXS 0506+056 (2018, background): “They are thus potentially capable of producing neutrinos with higher efficiency and luminosity compared to BL Lac objects (see e.g. Murase et al. 2014; Rodrigues et al. 2018).”
The Blazar TXS 0506+056 Associated with a High-energy Neutrino: Insights into Extragalactic Jets and Cosmic-Ray Acceleration (2018, background): “FSRQs are generally considered to be promising sources of high-energy neutrinos, on account of the inferred high density of target photons for the pγ channel (Atoyan & Dermer 2001; Murase et al. 2014).”