2017MNRAS.468.4000C

Black holes have been detected with masses less than 10² and greater than 10⁵ M_☉, but black holes with masses in the intermediate range are conspicuously absent. However, recent estimates of the mass of HLX-1, currently the strongest intermediate mass black hole (IMBH) candidate, suggest an approximate mass of 10⁴ M_☉, and recent estimates of the mass of M82 X-1 suggest a mass of 4 x 10², placing them within the missing black hole range. This raises the question of whether these are unique objects or if many more of these objects should be expected. We estimate the number of HLX-1 like IMBHs expected within the distance of 100 Mpc to be within an order of ≃10⁶, or ≃10² IMBHs within a galaxy, and about two orders of magnitude more when considering less massive IMBHs using M82 X-1 as a prototype. In the process of estimating this value, we determine the form of the mass function within the sphere of influence of a newly formed IMBH to be a power law with a slope of -1.83. Furthermore, we find that we are only able to fit both the period and luminosity of HLX-1 with a stellar companion with a mass between ≃10 and 11 M_☉, a result that is fairly robust to the mass of the IMBH between 10³ and 10⁵ M_☉.