Free Access

Fig. 5


Hardness ratio and Galactic NH distribution of X-ray sources with optical or infrared catalogue counterparts with identification probability >0.9 (large grey dots and grey-filled histograms), and of X-ray sources without catalogue counterpart or with identification probability below 0.9 (small black dots and empty black histograms). We only considered sources with good X-ray quality (sum_flag = 0) and with errors smaller than 0.3 in X-ray colours. Blue and red lines show the expected position of AGNs (Γ = 1.9) and stars (70 Myr old population, see Sect. 2.2 for details) respectively. Most of the objects with no infrared or optical counterpart follow a distribution similar to that of AGNs.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.