A Neutral Beam Model for High-energy Neutrino Emission from the Blazar TXS 0506+056

Abstract

The IceCube collaboration reported a ∼ 3.5σ excess of 13 ± 5 neutrino events in the direction of the blazar TXS 0506+056 during a ∼6 month period in 2014-2015, as well as the (∼ 3σ) detection of a high-energy muon neutrino during an electromagnetic flare in 2017. We explore the possibility that the 2014-2015 neutrino excess and the 2017 multi-messenger flare are both explained in a common physical framework that relies on the emergence of a relativistic neutral beam in the blazar jet due to interactions of accelerated cosmic rays (CRs) with photons. We demonstrate that the neutral beam model provides an explanation for the 2014-2015 neutrino excess without violating X-ray and γ-ray constraints, and also yields results consistent with the detection of one high-energy neutrino during the 2017 flare. If both neutrino associations with TXS 05065+056 are real, our model requires that (i) the composition of accelerated CRs is light, with a ratio of helium nuclei to protons 5, (ii) a luminous external photon field (∼ 10 46 erg s −1 ) variable (on year-long timescales) is present, and (iii) the CR injection luminosity as well as the properties of the dissipation region (i.e., Lorentz factor, magnetic field, and size) vary on year-long timescales.

3HSP J095507.9+355101: A flaring extreme blazar coincident in space and time with IceCube-200107A

“…In the presence of multiple emitting zones, and/or an obscuring medium for the γ-rays, the constraint of Eq. (1) can be relaxed and larger neutrino luminosity may be produced by 3HSP J095507.9+355101 (see for example such models for the 2017 flare of TXS 0506+056: Murase et al 2018;Liu et al 2019;Oikonomou et al 2019;Xue et al 2019;Zhang et al 2020).…”

Multifrequency Observations of the Candidate Neutrino-emitting Blazar BZB J0955+3551

“…erg cm −2 s −1 . This is contrary to the case of TXS 0506+056, where the comoving electron synchrotron radiation field being the dominant target photon field for photopion production to produce a significant flux of VHE neutrinos could be safely ruled out (see, e.g., Keivani et al 2018;Reimer et al 2019;Rodrigues et al 2019;Zhang et al 2020).…”

“…From a theoretical perspective, Reimer et al (2019) proposed that there should not be strongly correlated γ-ray and neutrino activity, and that neutrino production activity (through associated cascading) might actually show up more clearly in X-rays. However, the conclusion about the γ-ray/PeV neutrino correlation is reported to be model-dependent (see, e.g., Rodrigues et al 2019;Zhang et al 2020).…”

Leptonic and Hadronic Radiative Processes in Supermassive-Black-Hole Jets

“…In presence of dense photon fields they can trigger additional photo-meson production, or they can decay into protons (with a life-time of γ n × 880 seconds) and radiate again synchrotron photons in the presence of magnetic fields. This "neutral beam" model has drawn attention for its possibility to naturally produce two separate emitting regions in the jet, physically separated but casually connected [160,161].…”