XMM-Newton and NuSTAR Observations of the Compact Millisecond Pulsar Binary PSR J1653-0158

Abstract

We have presented the first joint XMM-Newton and NuSTAR analysis of the millisecond pulsar (MSP) binary PSR J1653-0158. The 75 minute orbital period inferred from optical and gamma-ray observations together with the 1.97 ms pulsation in the gamma-rays indicate that this system is the most compact Black Widow MSP system known to date. The orbital period was not detected in the XMM-Newton and NuSTAR data, probably due to insufficient photon counts obtained in the observations. Fitting the joint X-ray spectrum of PSR J1653-0158 with a power law gives a photon index Γ = 1.71 ± 0.09. The X-ray luminosity of the source in the (0.2-40) keV band is deduced to be 1.18 × 10³¹ erg s^-1, for an adopted distance of 0.84 kpc. We have shown that the broadband X-ray spectrum can be explained by synchrotron radiation from electrons accelerated in the intrabinary shock, and the gamma-rays detected in the Fermi data are curvature radiations from electrons and positrons in the pulsar magnetosphere. Our kinematic analysis of the Tidarren systems PSR J1653-0158 and PSR J1311-3430 indicates that the two Tidarren systems are likely to have originated in the Galactic disk.