Simulation map of the X-ray flux in the 0.5−7 keV band, same as in Fig. 1. Overplotted, the four hexagonal X-IFU-like pointings, centered on the faintest regions discussed in Sect. 4.1.2 (z1, z2, z3 and z5) – marked here as thin green squares for comparison. The X-IFU hexagonal pointing covers a region of 5′ equivalent diameter (corresponding to ∼330 kpc at the fiducial redshift of z = 0.057).