A New Measurement of the Spin and Orbital Parameters of the High Mass X-ray Binary Centaurus X-3 using AstroSat

TL;DR

This paper reports new timing measurements of the high-mass X-ray binary Centaurus X-3 using AstroSat, revealing details about its spin period, orbital parameters, and accretion disk dynamics.

Contribution

It provides the first detailed timing analysis of Centaurus X-3 with AstroSat, including measurements of spin period, spin-up timescale, and orbital parameters.

Findings

Confirmed pulse profile with prominent peak and inter-pulse

Measured spin period of 4.80188 seconds with spin-up trend

Derived orbital parameters indicating negative torque effects

Abstract

We present the timing results of out-of-eclipse observations of Centaurus X-3 spanning half a binary orbit, performed on 12-13 December, 2016 with the Large Area X-ray Proportional Counter (LAXPC) on-board AstroSat. The pulse profile was confirmed to exhibit a prominent pulse peak with a secondary inter-pulse. The systemic spin period of the pulsar was found to be $4.80188 \pm 0.000085$ s in agreement with its spin up trend. The spin up timescale seems to have increased to $7709 \pm 58$ yr that points to negative torque effects in the inner accretion disk. We also report the derived values of projected semi-major axis and orbital velocity of the neutron star.