Xmm-newton Sets the Record Straight: No X-ray Emission Detected from Psr J0631+1036

The pulsar PSR J0631+1036 was discovered during a radio search of Einstein X-ray source error circles. A detection of a 288ms sinusoidal modulation in the ASCA lightcurve, the same period as the radio pulsar, appeared to confirm the association of the X-ray source and the pulsar. Its X-ray spectrum was said to be similar to that of middle aged γ-ray pulsars such as Geminga. However, an XMM-Newton observation of the PSR J0631+1035 field, along with a re-analysis of VLA data confirming the timing position of the pulsar, show a 75 discrepancy in location of the X-ray source and the pulsar, and therefore these cannot be the same object. The X-ray source appears to be the counterpart of an A0 star, detected by the XMMNewton Optical Monitor. No 288ms period was detected from either the area around the pulsar or the bright Xray source. The upper limit on the X-ray luminosity with relation to the empirically observed correlation between radio measured dE/dt and X-ray luminosity is discussed.