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R.E. Griffiths, T. Miyaji (CMU), G. Hasinger, Y. Hashimoto, G. Szokoly (AIP), M.J.L.T. Turner, R.S. Warwick, M.G. Watson (U.Leicester), F. Paerels (SRON), K. Mason, M.J. Page (MSSL), J. Trumper, K. Dennerl (MPE), F. Jansen, D. Lumb, N. Schartel (ESTEC), J. Bergeron, P. Rosati (ESO), P. Ferrando (CENS), M. Dadina (IFC Milan), T. Sasseen (UCB), X. Barcons (U.Cantabria), R. McMahon (ICST)
The power of XMM-Newton for studies of the X-ray background and of the cosmological evolution of X-ray source populations is vividly demonstrated by the first deep survey performed in the Payload Verification phase. The Lockman Hole survey illustrates the advantages of the collecting area of XMM-Newton for the measurement of individual source spectra for fluxes as low as 10-14 cgs, sources at the detection limit of the Einstein deep surveys.
The combined X-ray image from the three telescopes on board XMM-Newton shows the changing nature of the X-ray universe in going from the soft regime of Einstein and ROSAT to the wider and harder reach of the replicated mirrors.
The extragalactic number counts, log(N)/log(S), have been accumulated in separate energy channels, 0.5 - 2 keV, 2 - 10 keV, and 5 - 10 keV. In the 2 - 10 keV band, the data clearly show a break to a flatter slope for source fluxes falling near or below 10-14 cgs. In the hard 5 - 10 keV band, the deviation from a Euclidean slope is not yet in evidence.
Identifications in this field are already known, for many cases, from the optical follow-up to the ROSAT study of this region. Spectra of the individual brighter AGN and narrow-line galaxies show discrete features in some cases, interpreted as iron line emission. The low-energy spectral cut-offs for the NLG's show evidence of cold gas absorption through column densities in the range 3 \times 1021 to 1023 cm-2.
This work was supported by both ESA and NASA.