Accretion-disc and double-X-ray-source geometry in REFLEX (not to scale). The outer radius of the thin annulus representing the AD is set as R_disc = R_out − R_in, with R_in = 1pc, and the inner radius of the annulus as r_disc = 6r_g. We place a double X-ray point source above and below the centre of the annulus at h_source = 10r_g. The grey area represents the cone defined by h_source and r_disc, inside which we do not allow the sources to emit, as in reality emission through the centre of the annulus would be blocked by the SMBH. The half-opening angle of the cone, θ_cone = arctan(r_disc / h_source), is denoted by the dashed lines.