Median overionisation profile as a function of the distance from the QSO (black line, grey area gives upper and lower quartiles) hosted by a halo at z = 3.0 (left) and z = 4.9 (right side) for a QSO luminosity L_νLL = 1  ×  10³¹   erg   Hz^-1   s^-1. The analytical overionisation profile including the SED effects is given by the solid line without the grey area. The region affected by oversampling (r < 1   Mpc) is marked with a dotted line.