Constraints on the mass and abundance of black holes in the Galactic halo: the high-mass limit |
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| Authors: | Chigurupati Murali † Phil Arras Ira Wasserman |
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| Institution: | Canadian Institute for Theoretical Astrophysics, McLennan Labs, University of Toronto, 60 St George St., Toronto M5S 3H8, Canada; Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853, USA |
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| Abstract: | We establish constraints on the mass and abundance of black holes in the Galactic halo by determining their impact on globular clusters, which are conventionally considered to be little evolved. Using detailed Monte Carlo simulations and simple evolutionary models, we argue that black holes with masses M bh?(1–3)×106 M⊙ can comprise no more than a fraction f bh≈0.17 of the total halo density at Galactocentric radius R ≈8 kpc. This bound arises from requiring stability of the cluster mass function. A more restrictive bound may be derived if we demand that the probability of destruction of any given, low-mass M c≈(2.5–7.5)×104 M⊙] globular cluster not exceed 50 per cent; this bound is f bh?0.025–0.05 at R ≈8 kpc. This constraint improves those based on disc heating and dynamical friction arguments as well as current lensing results. At smaller radius the constraint on f bh strengthens, while at larger radius an increased fraction of black holes is allowed. |
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| Keywords: | globular clusters: general Galaxy: halo Galaxy: structure dark matter |
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