Analysis of γ-ray emission above 30 GeV from the LMC pulsar wind nebula N 157B with Fermi-LAT

Abstract

ABSTRACT N 157B located in the Large Magellanic Cloud is the first pulsar wind nebula detected outside of the Galaxy in γ-rays. In this paper, we analyse the emission above 30 GeV from N 157B using ∼14.3 yr of Fermi-LAT data. The γ-ray spectrum between 30 and 500 GeV is well described by a single power-law function with a photon index of 1.83 ± 0.26, and its integral photon flux is (4.10 ± 0.83) × 10−11 photons cm−2 s−1. We adopt a one-zone leptonic model to investigate whether the multiband non-thermal emission of the target source can be generated by synchrotron radiation and inverse-Compton scattering of the electrons/positrons. Assuming the electrons/positrons in the nebula have a broken power-law spectrum with two breaks, the model can reproduce the observed fluxes in the radio, X-ray, and γ-ray bands. This result indicates that the γ-ray emission from N 157B can be explained by the leptonic process of electrons/positrons via inverse-Compton scattering.