eFEDS 0.5–2 keV flux vs. XMM-ATLAS flux upper-limit (3σ confldence) in the 0.5–2 keV. Each data point in this plot corresponds to an eFEDS source detection without a counterpart in the eFEDS source catalogue. For these sources, the 3σ flux upper limits are estimated from the XMM-ATLAS observations and plotted on the vertical axis. The solid blue line indicates the one-to-one relation. The dotted blue line corresponds to a factor of two in flux relative to the one-to-one relation, i.e. sources with XMM-ATLAS 3σ flux upper limits that are twice fainter than the XMM-ATLAS source flux. Sources below this line are highlighted in blue. Their properties are listed in Table 6.