2018MNRAS.478.3987K

We present the first results from a joint XMM-Newton and NuSTAR observation of the gamma-ray emitting millisecond pulsar compact binary PSR J2129-0429. X-ray emission up to about 40 keV is detected and the joint spectrum can be modelled with a power-law plus a neutron star atmosphere model. At a distance of 1.4 kpc, the 0.3-79 keV luminosity is 3.56 x 10³² erg s^–1. We also detected a 0.64-d binary orbital period with a double-peaked structure across the wavebands. By combining the updated Fermi GeV data, we modelled the broad-band spectral energy distribution as well as the X-ray modulation with an intrabinary model involving shock interaction between pulsar wind and outflow from the companion star. Lastly, we report a high-resolution X-ray image provided by Chandra to rule out the proposed pulsar wind nebula associated with PSR J2129-0429.