Centaurus X-3 orbital ephemerides using Insight-HXMT, RXTE, Swift/BAT, and NuSTAR observations

¹ Institut für Astronomie und Astrophysik, Sand 1, 72076 Tübingen, Germany
e-mail: klawin@astro.uni-tuebingen.de
² School of Physics and Astronomy, Sun Yat-Sen University, Zhuhai 519082, PR China
³ Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, PR China
⁴ University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, PR China

Received: 11 October 2022
Accepted: 4 April 2023

Abstract

Centaurus X-3 (Cen X-3) is the first X-ray pulsar discovered and has been studied for decades by multiple facilities, allowing for accurate measurements of the decay rate of the orbital period of the binary system. However, the most recent study of the orbital parameters of the system dates back to the RXTE era. For this study, we have complemented these measurements with the more recent high-quality Insight-HXMT and NuSTAR data obtained 20 yr later to improve constraints on the orbital period decay rate and eccentricity of the system through pulsar timing analysis. In addition, we also used long-term monitoring by Swift/BAT to independently measure orbital period evolution through eclipse timing. As a result, improved orbital ephemerides including accurate estimates of the orbital period, the period decay rate, and eccentricity of the system were obtained.