The spin and orbit of the newly discovered pulsar IGR J17480-2446

Abstract

We present an analysis of the spin and orbital properties of the newly discovered accreting pulsar IGR J17480-2446, located in the globular cluster Terzan 5. Considering the pulses detected by the Rossi X-ray Timing Explorer at a period of 90.539645(2) ms, we derive a solution for the 21.27454(8) hr binary system. The binary mass function is estimated to be 0.021275(5) M⊙, indicating a companion star with a mass larger than 0.4 M⊙. The X-ray pulsar spins up while accreting at a rate of between 1.2 and 1.7 × 10-12 Hz s-1, in agreement with the accretion of disc matter angular momentum given the observed luminosity.