On the Detection Potential of Blazar Flares for Current Neutrino Telescopes

Abstract

Blazar jets are extreme environments, in which relativistic proton interactions with an ultraviolet photon field could give rise to photopion production. High-confidence associations of individual highenergy neutrinos with blazar flares could be achieved via spatially and temporally coincident detections. In 2017, the track-like, extremely high-energy neutrino event IC 170922A was found to coincide with increased γ-ray emission from the blazar TXS 0506+056, leading to the identification of the most promising neutrino point source candidate so far. We calculate the expected number of neutrino events that can be detected with IceCube, based on a broadband parametrization of bright short-term blazar flares that were observed in the first 6.5 years of Fermi /LAT observations. We find that the integrated keV-to-GeV fluence of most individual blazar flares is far too small to yield a substantial Poisson probability for the detection of one or more neutrinos with IceCube. We show that the sample of potentially detectable high-energy neutrinos from individual blazar flares is rather small. We further show that the blazars 3C 279 and PKS 1510−089 dominate the all-sky neutrino prediction from bright and short-term blazar flares. In the end, we discuss strategies to search for more significant associations in future data unblindings of IceCube and KM3NeT.

Assessing coincident neutrino detections using population models

“…Aartsen et al 2016b;Neronov et al 2017;Bartos et al 2021). There are also more detailed theoretical investigations of individual blazars, for which the constraints on the hadronic fraction of γ-ray emission are strong (Oikonomou et al 2019;Palladino et al 2019;Kreter et al 2020).…”

“…This is challenging due to the limited amount of simultaneous X-ray and γ-ray observations of blazar flares (see e.g. Kreter et al 2020).…”

“…Indeed, SED modelling of the multiwavelength spectra of TXS 0506+056 indicate that it is challenging to reach expected event numbers of O(1) for this particular source, without overshooting the X-ray measurements or invoking multizone models (Keivani et al 2018;Cerruti et al 2018;Gao et al 2019;Xue et al 2019;Liu et al 2019). Additionally, studies on the modelling of similar blazar flares show expected neutrino event numbers of 1 for individual sources (Oikonomou et al 2019;Palladino et al 2019;Kreter et al 2020). With this in mind, we allow for the expected number of neutrino events from TXS 0506+056 to be < 1 and explore the blazar-neutrino connection in this case.…”

Multiwavelength and Multimessenger Observations of Blazars and Theoretical Modeling: Blazars as Astrophysical Neutrino Sources

“…A phenomenological, calorimetric estimate of the expected neutrino flux by [26] found a very small probability of an IceCube neutrino detection during multi-wavelength flares of this source. More detailed physical modeling of the SED and neutrino production through photo-hadronic processes was performed by [14].…”

Constraints on magnetic field and particle content in blazar jets through optical circular polarization

“…3C 279 and PKS 1510−089 are famous for their bright outbursts, high variable emission, extreme polarization behavior as well as potentially multimessenger emission (Marscher et al 2010;Abdo et al 2010;Ackermann et al 2016;Kreter et al 2020;Blinov et al 2021b). The sources were observed during the nights of the 7, 8, 10 and 11th of April 2021, using the HIgh-speed Photo-POlarimeter(HIPPO; Potter et al 2010) on the 1.9-m telescope of the South African Astronomical Observatory.…”