log    N(>S) − log    S curves in the soft band (0.5–2 keV, left panel) and the hard band (2–12 keV, right panel) for all detected X-ray sources (grey), identified active coronae with P_id > 90% (solid red lines) and unidentified plus extragalactic sources (solid blue blue). Sources either identified as active stars or with P_id higher than 90% are shown with red dotted lines, and sources either identified as extragalactic or unidentified sources with no infrared and no optical counterpart are shown with blue dotted lines. We show the expected contribution of extragalactic sources from Campana et al. (2001) plus Hasinger et al. (1998) in the soft band, and from Mateos et al. (2008) and Campana et al. (2001) in the hard band.