Orbital parameters of V 0332+53 from 2015 giant outburst data

TL;DR

This paper refines the orbital parameters of the Be X-ray binary V 0332+53 using data from the 2015 outburst, showing no need for orbital changes to explain spin evolution and confirming accretion torque predictions.

Contribution

It provides an improved orbital solution for V 0332+53 and demonstrates that previous orbital parameters remain valid during recent outbursts.

Findings

No change in orbital parameters needed to explain spin evolution.

Intrinsic spin-up consistent with accretion torque theory.

Enhanced constraints on orbital parameters.

Abstract

We present the updated orbital solution for the transient Be X-ray binary V 0332+53 comple- menting historical measurements with the data from the gamma-ray burst monitor onboard Fermi obtained during the outburst in June-October 2015. We model the observed changes in the spin- frequency of the pulsar and deduce the orbital parameters of the system. We significantly improve existing constrains and show that contrary to the previous findings no change in orbital parameters is required to explain the spin evolution of the source during the outbursts in 1983, 2005 and 2015. The reconstructed intrinsic spin-up of the neutron star during the latest outburst is found to be comparable with previosly observed values and predictions of the accretion torque theory.