Multiwavelength coverage of the 2024 periastron passage of PSR B1259-63 / LS 2883

TL;DR

This study presents multiwavelength observations of PSR B1259-63 during its 2024 periastron, revealing variability in emissions linked to the decretion disk size and structure, with notable X-ray and GeV flaring behaviors.

Contribution

First comprehensive multiwavelength campaign on PSR B1259-63's 2024 periastron, linking disk size variations to emission patterns and flare structures.

Findings

Early X-ray flaring before periastron.

Post-periastron GeV emission detected.

X-ray/radio correlation observed during post-periastron rise.

Abstract

PSR B1259-63 is a gamma-ray binary system with a 48 ms radio pulsar orbiting around an O9.5Ve star, LS 2883, in a highly eccentric ~3.4 yr long orbit. Close to the periastron the system is detected from radio up to the TeV energies due to the interaction of LS 2883 and pulsar's outflows. The observations of last 4 periastra passages taken in 2010-2021 demonstrate periastron to periastron variability at all wavelength, probably linked to the state of the decretion disk. In this paper we present the results of our optical, radio and X-ray observational campaigns on PSR B1259-63 performed in 2024 accompanied with the analysis of the publicly available GeV FERMI/LAT data. We show that this periastron passage was characterised by the early flaring of X-rays before the periastron passage and GeV emission after the periastron passage, which can be explained by a larger size of the decretion disk as supported by the optical observations. The structure of the GeV flare is also in agreement with the disruption of the large dense disk. The possible X-ray/radio correlation was observed only during the post-periastron rise of X-ray and radio emission.