Ultrahigh-energy Gamma-Ray Radiation from the Crab Pulsar Wind Nebula

TL;DR

This study investigates the origins of high-energy gamma-ray emission from the Crab nebula, exploring leptonic and hybrid models, and finds potential hadronic contributions at PeV energies, suggesting future observations could reveal more about its radiation mechanisms.

Contribution

It introduces a comprehensive analysis using MCMC sampling to evaluate leptonic and hybrid models for Crab nebula gamma-ray emission, highlighting potential hadronic contributions at ultra-high energies.

Findings

Pure leptonic models partly fit the data.

Hadronic processes may dominate above PeV energies.

Future observations could detect higher energy signals.

Abstract

It has been long debated whether the high-energy gamma-ray radiation from the Crab nebula stems from leptonic or hadronic processes. In this work, we investigate the multi-band non-thermal radiation from the Crab pulsar wind nebula with the leptonic and leptonic-hadronic hybrid models, respectively. Then we use the Markov Chain Monte Carlo(MCMC) sampling technology and method of sampling trace to study the stability and reasonability of the model parameters according to the recent observed results and obtain the best-fitting values of parameters. Finally, we calculate different radiative components generated by the electrons and protons in the Crab nebula. The modeling results indicate that the pure leptonic origin model with the one-zone only can partly agree with some segments of the data from various experiments (including the $\rm PeV$ gamma-ray emission reported by the LHAASO and the other radiation ranging from the radio to very high energy (VHE) gamma-ray waveband), and the contribution of hadronic interaction is hardly constrained. However, we find that the hadronic process may also contribute, especially in the energy range exceeding the $\rm PeV$. In addition, it can be inferred that the higher energy signals from the Crab nebula could be observed in the future.