2019MNRAS.482.2149L

We present near-infrared and optical imaging of 15 candidate black hole X-ray binaries. In addition to quiescent observations for all sources, we also observed two of these sources (IGR J17451-3022 and XTE J1818-245) in outburst. We detect the quiescent counterpart for 12 out of 15 sources, and for the remaining 3, we report limiting magnitudes. The magnitudes of the detected counterparts range between K_s = 17.59 and K_s = 22.29 mag. We provide (limits on) the absolute magnitudes and finding charts of all sources. Of these 12 detections in quiescence, 7 detections represent the first quiescent reported values (for MAXI J1543-564, XTE J1726-476, IGR J17451-3022, XTE J1818-245, MAXI J1828-249, MAXI J1836-194, Swift J1910.2-0546), and 2 detections show fainter counterparts to XTE J1752-223 and XTE J2012+381 than previously reported. We used theoretical arguments and observed trends, for instance between the outburst and quiescent X-ray luminosity and orbital period P_orb to derive an expected trend between ΔK_s and P_orb of ΔK_ s_ ∝logP_ orb_^0.565. Comparing this to observations, we find a different behaviour. We discuss possible explanations for this result.