The radio to GeV picture of PSR B1259-63 during the 2021 periastron passage

TL;DR

This paper studies the multi-wavelength emission of PSR B1259-63 during its 2021 periastron, revealing new features and comparing with past passages to understand the system's complex interaction dynamics.

Contribution

It provides new observational data from 2021 and applies a 2-zone emission cone model to explain the evolving emission features.

Findings

Detection of a third X-ray peak in 2021 periastron

Disappearance of radio/X-ray flux correlation after the third peak

Comparison of 2021 data with previous periastra to understand emission variability

Abstract

PSR B1259-63 is a gamma-ray binary system with a radio pulsar orbiting an O9.5Ve star, LS 2883, with a period of ~3.4 yr. Close to the periastron the system is detected at all wavelengths, from radio to the TeV energies. The emission in this time period is believed to originate from the interaction of LS 2883 and pulsar's outflows. The observations of 4 periastra passages taken in 2010-2021 show strong correlation of the radio and X-ray lightcurves with two peaks just before and after the periastron. The observations of the latest 2021 periastron passage reveal the presence of the 3rd X-ray peak and subsequent disappearance of radio/X-ray flux correlation. In this paper we present the results of our optical, radio and X-ray observational campaigns on PSR B1259-63 performed in 2021 accompanied with the analysis of the publicly available GeV FERMI/LAT data. We compare the properties of different periastron passages, discuss the obtained results and show that they can be explained in terms of the 2-zone emission cone model proposed by us previously.