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Simulations of high-energy neutrino emissions from blazars with the LeHa-Paris code

Francesco Carenini, Matteo Cerruti

TL;DR

The paper targets the problem of identifying and characterizing blazar sources of high-energy neutrinos by employing the LeHa-Paris one-zone leptohadronic code to model photon and neutrino emission, with PKS 2155-304 as the testbed. Through a $\chi^2$ optimization, it derives best-fit hadronic parameters and demonstrates that the all-flavor neutrino SED can peak near $E_\nu \approx 100$ PeV, while the jet power remains super-Eddington yet physically plausible for a $M_{\mathrm{BH}} \sim 10^9\,M_\odot$ black hole. The authors then extend these neutrino flux templates to the 3HSP HBL population via redshift and synchrotron-peak flux rescaling, enabling rapid predictions for many sources, and validate the approach by applying it to Mrk 421 and VER J0521+211 with reasonable agreement in the PeV range. These results provide practical templates for current and upcoming neutrino telescopes, such as KM3NeT/ARCA, and support stacking analyses across blazar populations to test hadronic neutrino production.

Abstract

The identification of astrophysical sources responsible for high-energy cosmic neutrinos has long been a challenge. A significant milestone was achieved with the blazar TXS 0506+056, which was found to be in a flaring state of high gamma-ray emission and associated at the 3$σ$ level with a 290 TeV neutrino detected by IceCube in September 2017. This discovery motivated deeper exploration of the theoretical link between photon and neutrino emissions. In this context, simulations of proton-photon interactions in blazars and radiative processes are conducted using advanced numerical codes to predict neutrino spectra. The LeHa-Paris code, previously applied to TXS 0506+056, enables the computation of both leptonic and hadronic components of blazar spectral energy distributions, facilitating exploration of a broad parameter space. In this work, starting from the case of PKS 2155-304, one of the brightest and most studied High-frequency-peaked BL Lacs (HBLs), known for its extreme variability and subject of multi-wavelength observational campaigns, a methodology has been developed to extend neutrino flux templates, optimized via LeHa-Paris, to the full class of HBLs. Afterwards, neutrino emission models for a subset of HBLs from the 3HSP catalogue are derived.

Simulations of high-energy neutrino emissions from blazars with the LeHa-Paris code

TL;DR

The paper targets the problem of identifying and characterizing blazar sources of high-energy neutrinos by employing the LeHa-Paris one-zone leptohadronic code to model photon and neutrino emission, with PKS 2155-304 as the testbed. Through a optimization, it derives best-fit hadronic parameters and demonstrates that the all-flavor neutrino SED can peak near PeV, while the jet power remains super-Eddington yet physically plausible for a black hole. The authors then extend these neutrino flux templates to the 3HSP HBL population via redshift and synchrotron-peak flux rescaling, enabling rapid predictions for many sources, and validate the approach by applying it to Mrk 421 and VER J0521+211 with reasonable agreement in the PeV range. These results provide practical templates for current and upcoming neutrino telescopes, such as KM3NeT/ARCA, and support stacking analyses across blazar populations to test hadronic neutrino production.

Abstract

The identification of astrophysical sources responsible for high-energy cosmic neutrinos has long been a challenge. A significant milestone was achieved with the blazar TXS 0506+056, which was found to be in a flaring state of high gamma-ray emission and associated at the 3 level with a 290 TeV neutrino detected by IceCube in September 2017. This discovery motivated deeper exploration of the theoretical link between photon and neutrino emissions. In this context, simulations of proton-photon interactions in blazars and radiative processes are conducted using advanced numerical codes to predict neutrino spectra. The LeHa-Paris code, previously applied to TXS 0506+056, enables the computation of both leptonic and hadronic components of blazar spectral energy distributions, facilitating exploration of a broad parameter space. In this work, starting from the case of PKS 2155-304, one of the brightest and most studied High-frequency-peaked BL Lacs (HBLs), known for its extreme variability and subject of multi-wavelength observational campaigns, a methodology has been developed to extend neutrino flux templates, optimized via LeHa-Paris, to the full class of HBLs. Afterwards, neutrino emission models for a subset of HBLs from the 3HSP catalogue are derived.

Paper Structure

This paper contains 7 sections, 1 equation, 3 figures, 4 tables.

Table of Contents

  1. Introduction
  2. LeHa-Paris code
  3. The case of PKS 2155-304
  4. Model optimization
  5. Extension to astrophysical catalogues
  6. Model validation
  7. Conclusions and perspectives

Figures (3)

  • Figure 1: SED of PKS 2155-304 for the best-fit model, compared to data from Madejski:2016evb and HESS:2020. Associated parameters are reported in Table \ref{['tab:paropt']}. The all-flavor neutrino SED is reported as a blue solid line. Radiation components not shown in the plot are subdominant.
  • Figure 2: Mrk 421 SED based on parameters reported in Table \ref{['tab:parmrk']}. The light-blue line shows the neutrino emission predicted by the model; the red line shows the PKS 2155$-$304 template rescaled to Mrk 421. Radiation components not shown in the plot are subdominant. Data are taken from Balokovic:2016.
  • Figure 3: SED of VER J0521+211 based on parameterers reported in Table \ref{['tab:parver']}. The blue solid line is the neutrino spectrum of the model, while the solid red corresponds to PKS 2155$-$304 template rescaled to this source. Radiation components not shown in the plot are subdominant. Data are taken from VERITAS_MAGIC:2022.