The orbital parameters of gamma-ray binary PSR~J2032+4127

TL;DR

This paper analyzes 16 years of Fermi satellite data to precisely determine the highly eccentric orbital parameters of the gamma-ray binary PSR J2032+4127, including its period, eccentricity, and inclination.

Contribution

It provides the first precise measurement of the orbital parameters of PSR J2032+4127 using gamma-ray pulsation timing data.

Findings

Orbital period of approximately 52.3 years.

Eccentricity of about 0.98.

Detection of a small glitch in 2021.

Abstract

PSR~J2032+4127 is the only one of gamma-ray binary, that exhibits pulsations in gamma-ray. Previous research has indicated that the pulsar and the Be star MT91 213 orbit each other in a highly eccentric orbit with an extremely long period, with the pulsar reaching its periastron on November 13, 2017. Since its launch, the \fermi{} satellite has been monitoring this pulsar for 16 years, covering the 8 years before and the 8 years after the pulsar passed its periastron. Using these data, we present an analysis of pulse arrival times, and precisely determine the orbital parameters for the first time: the orbital period of $P_{\rm orb} \sim 52.3$ yr, the eccentricity of $e \sim 0.98$, the semimajor axis of $a$sin$i \sim 25.3$ AU, and the orbital inclination of $\sim$ 47.1$^\circ$ -- 55.1$^\circ$. We also reveal another small glitch occurred in 2021, MJD $\sim$ 59500.