Ic10 X-1: the Immediate Progenitor of a Double Black Hole Binary

We follow the evolution of IC10 X-1, the extragalactic binary hosting the most massive known stellar black hole with the mass of at least 23 M⊙. A massive companion of this black hole is a 35 M⊙ helium star that will very soon form another black hole. We demonstrate that this system will become a close double black hole binary with coalescence time of ∼ 2 − 3Gyr. We estimate that a detection rate of such systems is of the order of 0.5 yr for initial LIGO and VIRGO. Additionally, we point out that the existence of a 23 M⊙ black hole in the small metallicity environment of IC10 constrains the mass loss rates from massive stars to ∼ 50% of currently used values. Subject headings: binaries: close — black hole physics — gravitational waves — stars: evolution — stars: neutron