The likely detection of pulsed high-energy gamma-ray emission from millisecond pulsar PSR J0218+4232

TL;DR

This paper presents circumstantial evidence for the first detection of pulsed high-energy gamma-ray emission from the millisecond pulsar PSR J0218+4232, using EGRET data, showing a double-peaked pulse profile consistent with X-ray observations.

Contribution

It provides the first potential detection of gamma-ray pulsations from a millisecond pulsar, linking gamma-ray and X-ray pulse profiles and advancing understanding of pulsar emission mechanisms.

Findings

Gamma-ray emission spatially consistent with PSR J0218+4232

Detection of a double-peaked pulse profile in gamma rays

Pulse profile similar to X-ray observations

Abstract

We report circumstantial evidence for the first detection of pulsed high-energy gamma-ray emission from a millisecond pulsar, PSR J0218+4232, using data collected with the Energetic Gamma Ray Experiment (EGRET) on board the Compton Gamma Ray Observatory (CGRO). The EGRET source 3EG J0222+4253 is shown to be spatially consistent with PSR J0218+4232 for the energy range 100 - 300 MeV. Above 1 GeV the nearby BL Lac 3C 66A is the evident counterpart, and between 300 MeV and 1 GeV both sources contribute to the gamma-ray excess. Folding the 100-1000 MeV photons with an accurate radio ephemeris of PSR J0218+4232 yields a double peaked pulse profile with a ~3.5 sigma modulation significance and with a peak separation of ~0.45 similar to the 0.1-10 keV pulse profile.