XMM-Newton Spectral Energy Distribution of a New Candidate Isolated Neutron Star

Only seven isolated radioquiet neutron stars (XINS) emitting thermal X rays areknown, too few to address fundamental questions such as the equation of state ofdegenerate neutron matter. To expand this sample, we have used the Sloan DigitalSky Survey (SDSS) to examine 10,000 ROSAT error circles and identify a dozenXray sources lacking plausible optical counterparts. Short Chandra observationsof these XINS candidates are underway to pinpoint the sources. The very smallChandra error circle of one observed candidate remains completely opticallyblank in SDSS, and this ROSAT/Chandra source is a prime new XINS candidate. Wepropose a 15 ksec XMM observation to obtain high quality Xray SED informationthat will elucidate the nature of this intriguing blankfield Xray source. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]