Energy-dependent flavor ratios, cascade/track spectrum tension and high-energy neutrinos from magnetospheres of supermassive black holes

Abstract

The IceCube neutrino observatory measures the diffuse flux of high-energy astrophysical neutrinos by means of various techniques, and there exists a mild tension between spectra obtained in different analyses. The spectrum derived from reconstruction of muon tracks is harder than that from cascades, dominated by electron and tau neutrinos. If confirmed, this tension may provide a clue to the origin of these neutrinos, which remains uncertain. Here we investigate the possibility that this tension may be caused by the change of the flavor content of astrophysical neutrinos with energy. We assume that at higher energies, the flux contains more muon neutrinos than expected in the usually assumed flavor equipartition. This may happen if the neutrinos are produced in regions of the magnetic field so strong that muons, born in pi-meson decays, cool by synchrotron radiation faster than decay. The magnetic field of $\sim 10^{4}G$ is required for this mechanism to be relevant for the IceCube results. We note that these field values are reachable in the immediate vicinity of supermassive black holes in active galactic nuclei and present a working toy model of the population of these potential neutrino sources. While this model predicts the required flavor ratios and describes the high-energy spectrum, it needs an additional component to explain the observed neutrino flux at lower energies.

6 pages, 4 figures; V2: discussion extended, results unchanged; version accepted by Phys. Lett. B

References in corpus (24)

• IceCube-Gen2: The Window to the Extreme Universe
• The IceCube high-energy starting event sample: Description and flux characterization with 7.5 years of data
• All-sky search for time-integrated neutrino emission from astrophysical sources with 7 years of IceCube data
• Characteristics of the diffuse astrophysical electron and tau neutrino flux with six years of IceCube high energy cascade data
• Improved Characterization of the Astrophysical Muon-Neutrino Flux with 9.5 Years of IceCube Data
• Flavor Composition and Energy Spectrum of Astrophysical Neutrinos
• The Pacific Ocean Neutrino Experiment
• Observational evidence for the origin of high-energy neutrinos in parsec-scale nuclei of radio-bright active galaxies
• KM3NeT: Towards a km3 Mediterranean Neutrino Telescope
• Dissecting the regions around IceCube high-energy neutrinos: growing evidence for the blazar connection
• High-Energy Neutrinos from Magnetized Coronae of Active Galactic Nuclei and Prospects for Identification of Seyfert Galaxies and Quasars in Neutrino Telescopes
• Directional association of TeV to PeV astrophysical neutrinos with radio blazars
• Energy dependent neutrino flavor ratios from cosmic accelerators on the Hillas plot
• Association of IceCube neutrinos with radio sources observed at Owens Valley and Metsähovi Radio Observatories
• Inferring the flavor of high-energy astrophysical neutrinos at their sources
• Toward determining the number of observable supermassive black hole shadows
• High-Energy Neutrinos from Active Galactic Nuclei
• Constraints on the models of the origin of high-energy astrophysical neutrinos
• Using High-Energy Neutrinos As Cosmic Magnetometers
• Cosmic Neutrino Flavor Ratios with Broken ${\nu }_{\mu }-{\nu }_{\tau }$ Symmetry
• Neutrino telescopes and high-energy cosmic neutrinos
• Gamma-ray and Neutrino Signals from Accretion Disk Coronae of Active Galactic Nuclei
• Towards a model of population of astrophysical sources of ultra-high-energy cosmic rays
• Radio astronomy locates the neutrino origin in bright blazars

Cited by in corpus (3)

• Neutrino production in blazar radio cores
• Signature of Collapsars as Sources for High-energy Neutrinos and $r$-process Nuclei
• Energy-dependent flavour ratios in neutrino telescopes from charm