A detailed study of the multiplicity properties of massive stars down to very low mass-ratios is of crucial importance to constrain massive star and binary formation theories. Past spectroscopic and interferometric multiplicity studies have not reached the contrasts needed to probe the low-mass end of the companion mass function around such massive objects. Recently, the Carina High-contrast Imaging Project of massive Stars (CHIPS) showed that with high-contrast imaging (VLT/SPHERE) we are able to explore the brown dwarf regime around massive stars at angular separations between 0”.15 and 6” (~400-15000 AU). These observations are not only important to constrain massive star and binary formation theories, but also allow us to understand whether low-mass companions can form in the harsh environment of UV radiation powered by the central massive star.
Concretely, I will present SPHERE observations of four brown dwarf (candidate) companions that we recently discovered around an O-type dwarf and a B-type supergiant in M17 and Sco OB1, respectively. These are the first brown dwarf companions that have been found (or imaged) around such massive objects, allowing us to explore for the first time the impact of massive star feedback on the formation and survival of substellar companions.