In low-metallicity environments , massive stars might avoid supernova explosion and directly collapse , forming massive ( \sim { } 25 - 80 { } M _ { \odot } { } ) stellar black holes ( MSBHs ) , at the end of their life .
MSBHs , when hosted in young massive clusters , are expected to form binaries and to strongly interact with stars , mainly via three-body encounters .
We simulate various realizations of young star clusters hosting MSBHs in hard binaries with massive stars .
We show that a large fraction ( \sim { } 44 per cent ) of MSBH binaries are ejected on a short timescale ( \leq { } 10 Myr ) .
The offset of the ejected MSBHs with respect to the parent cluster is consistent with observations of X-ray binaries and ultra-luminous X-ray sources .
Furthermore , three-body encounters change the properties of MSBH binaries : the semi-major axis changes by \leq { } 50 per cent and the eccentricity of the system generally increases .
We shortly discuss the implications of our simulations on the formation of high-mass X-ray binaries hosting MSBHs .