ORDINARY X-RAYS FROM THREE EXTRAORDINARY MILLISECOND PULSARS: XMM-NEWTON OBSERVATIONS OF PSRs J0337+1715, J0636+5129, AND J0645+5158

We present the first X-ray observations of three recently discovered millisecond pulsars (MSPs) with interesting characteristics: PSR J0337+1715, PSR J0636+5129, and PSR J0645+5158. PSR J0337+1715 is a fast-spinning, bright, and so-far unique MSP in a hierarchical triple system with two white dwarf companions. PSR J0636+5129 is an MSP in a very tight 96-minute orbit with a low-mass, 8 MJ companion. PSR J0645+5158 is a nearby, isolated MSP with a very small duty cycle (1%–2%), which has led to its inclusion in high-precision pulsar timing programs. Using data from XMM-Newton, we have analyzed X-ray spectroscopy for these three objects, as well as optical/ultraviolet photometry for PSR J0337+1715. The X-ray data for each are largely consistent with expectations for most MSPs with regards to the ratios of thermal and non-thermal emission. We discuss the implications of these data on the pulsar population, and prospects for future observations of these pulsars.