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

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.