Gaia detection limits for a non-luminous companions of 10 M_⊙ on a circular orbit around a F0V, G2V, and K2V star. The lines represent the (sky-uniform) median distance limit at which the Δχ² = 100 between a single star and a circular Keplerian orbital model fit, corresponding to (typically) well-constrained orbital fits. Estimates were provided for the 5 yr nominal mission (∼DR4) and 10 yr extended mission (∼DR5) as a function of period. Successful detections drop quickly for orbital periods longer than the data time-span, and the graphs are therefore truncated at 5 and 10 yr. At the top, the semi-major axis (a) is specified for a G2V star, although the difference for the other masses would be hardly noticeable. On the right side, we provide a rough estimate of the MW coverage for a specific distance limit, assuming a disk of height 1.15 kpc and radius 15 kpc, and we therefore obtain a full coverage at 23 kpc. All detection values assume zero extinction.