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In the Galaxy there are 71 Be X-ray binaries known to-date. Out of those, 48 host a neutron star, and for the reminder the nature of a companion is not known. None, so far, is known to host a black hole. This disparity is referred to as a missing Be – black hole X-ray binary problem. The stellar population synthesis calculations following the formation of Be X-ray binaries (Belczyński & Ziółkowski 2009) predict that the ratio of the binaries with neutron stars to the ones with black holes is rather high FNS/BH ∼ 30−50. The ratio is a natural outcome of (1) the stellar initial mass function that provides more neutron stars than black holes and (2) common envelope evolution (i.e. a major mechanism involved in the formation of interacting binaries) that naturally selects progenitors of Be X-ray binaries with neutron stars (comparable mass binaries have more likely survival probabilities) against ones with black holes (much more likely common envelope mergers). A comparison of this ratio with the number of confirmed Be – neutron star X-ray binaries (48) indicates that the expected number of Be – black hole X-ray binaries is of the order of only ∼ 0− 2. This is entirely consistent with the observed Galactic sample. Therefore, there is no problem of the missing Be+BH X-Ray Binaries for the Galaxy

On the Apparent Lack of Be X-ray Binaries with Black Holes in the Galaxy and in the Magellanic Clouds