# Leptohadronic blazar models applied to the 2014-15 flare of TXS 0506+056

## TL;DR

This study assesses leptohadronic models to explain neutrino emissions from blazar TXS 0506+056 during 2014-15, finding that models can account for a few neutrino events but struggle to match higher event counts without conflicting with electromagnetic observations.

## Contribution

The paper compares different leptohadronic models to explain neutrino emissions from TXS 0506+056, highlighting limitations in simultaneously fitting neutrino and electromagnetic data.

## Key findings

- Models can explain 1-5 neutrino events without conflicting with X-ray data.
- Higher neutrino event counts conflict with gamma-ray observations.
- No single model can fully reconcile neutrino and electromagnetic observations.

## Abstract

We investigate whether the emission of neutrinos observed in 2014-15 from the direction of the blazar TXS 0506+056 can be accommodated with leptohadronic multi-wavelength models of the source commonly adopted for the 2017 flare. While multi-wavelength data during the neutrino flare are sparse, the large number of neutrino events ($13\pm5$) challenges the missing activity in gamma rays. We illustrate that two to five neutrino events during the flare can be explained with leptohadronic models of different categories: a one-zone model, a compact core model, and an external radiation field model. If, however, significantly more events were to be accommodated, the predicted multi-wavelength emission levels would be in conflict with observational X-ray constraints, or with the high-energy gamma ray fluxes observed by the Fermi LAT, depending on the model. For example, while the external radiation field model can predict up to five neutrino events without violating X-ray constraints, the absorption of high-energy gamma rays is in minor tension with data. We therefore do not find any model that can simultaneously explain the high event number quoted by IceCube and the (sparse) electromagnetic data during the neutrino flare.