XMM-Newton observation of the Lockman Hole I. The X-ray data

We report on the first; deep X-ray survey with the XMM-Newton observatory d uring the performance verification phase. The field of the Lockman Hole, on e of the best studied sky areas over a very wide range of wavelengths, has been observed. A total of similar to 100 ksec good exposure time has been a ccumulated. Combining the images of the European Photon Imaging camera (EPI C) detectors we reach a flux limit of 0.31, 1.4 and 2.4 10(-15) erg cm(-2) s(-1), respectively in the 0.5-2, 2-10, and 5-10 keV band. Within an off-ax is angle of 10 arcmin we detect 148, 112 and 61 sources, respectively. The log(N)-log(S) relation in the three bands is compared with previous results . In particular in the 5-10 keV band these observations present the deepest X-ray survey ever, about a factor 20 more sensitive than the previous Bepp oSAX observations. Using X-ray spectral diagnostics and the set of previous ly known, spectroscopically identified ROSAT sources in the field, the new sources can be classified. XMM-Newton detects a significant number (similar to 40%) of X-ray sources with hard, probably intrinsically absorbed X-ray spectra, confirming a prediction of the population synthesis models for the X-ray background.