2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/2848Using 100ks of XMM-Newton data on the Lockman Hole, we show how the X-ray background 'spectral paradox' is being resolved. We find the summed spectra of the Type I AGN, Type II AGN, and the unidentified objects. We conclude that the hard slope of the XRB is caused predominantly by latter sources, i.e. the Type II AGN and unidentified objects.2 pages, 1 figure, to appear in the proceedings of the conference "New Century of X-ray Astronomy" held in Yokohama, Japan, March 2001Astrophysicstext