Impact of Parameters in the Blazar Jet Magnetic Field Model on Axion-Like Particle Constraints

TL;DR

This paper investigates how uncertainties in the magnetic field parameters of blazar jets affect constraints on axion-like particles, using multi-wavelength observations and gamma-ray spectra of Mrk 421.

Contribution

It introduces a method to incorporate jet magnetic field parameter uncertainties into ALP-photon oscillation constraints using multi-wavelength data.

Findings

Magnetic field parameters significantly influence ALP constraints.

Multi-wavelength fitting refines jet magnetic field models.

Results highlight the importance of accurate magnetic field modeling in ALP searches.

Abstract

The interaction between axion-like particles (ALPs) and photons induces ALP-photon oscillations in astrophysical magnetic fields, leading to spectral distortions in the $\gamma$-ray spectrum of blazars. The primary uncertainty of this phenomenon may originate from the magnetic field within the jet of the blazar. While many studies have explored the effects of ALP-photon oscillations using typical values for jet magnetic field parameters, it is important to recognize that these parameters can be constrained by multi-wavelength observations. In this study, we utilize the high energy $\gamma$-ray spectrum of Mrk 421 obtained from MAGIC and Fermi-LAT observations. By employing multi-wavelength fitting with a one-zone synchrotron self-Compton model, we derive the parameters characterizing the magnetic field model within the jet, and investigate their impacts on the ALP constraints.