机译:Statistical study of 2XMMi-DR3/SDSS-DR8 cross-correlation sample
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, 100012 Beijing, China;
Department of Astronomy, Peking University, 100871 Beijing, China;
catalogs; surveys; X-rays: diffuse background; X-rays: galaxies; X-rays: stars;