XMM‐Newton Observations of Four Millisecond Pulsars

Abstract

I present an analysis of the XMM-Newton observations of four millisecondpulsars, J0437-4715, J2124-3358, J1024-0719, and J0034-0534. The newdata provide strong evidence of thermal emission in the X-ray fluxdetected from the first three objects. This thermal component is bestinterpreted as radiation from pulsar polar caps covered with anonmagnetic hydrogen atmosphere. A nonthermal power-law component,dominating at energies E{\gt}~3 keV, can also be present in the detectedX-ray emission. For PSR J0437-4715, the timing analysis reveals that theshape and pulsed fraction of the pulsar light curves are energydependent. This, together with the results obtained from thephase-resolved spectroscopy, supports the two-component (thermal plusnonthermal) interpretation of the pulsar's X-ray radiation. Highlysignificant pulsations have been found in the X-ray flux of PSRsJ2124-3358 and J1024-0719. For PSR J0034-0534, a possible X-raycounterpart of the radio pulsar has been suggested. The inferredproperties of the detected thermal emission are compared withpredictions of radio pulsar models.