MACHO Project Limits on Black Hole Dark Matter in the 1-30 Solar Mass Range

摘要

We report on a search for long duration microlensing events towards the LargeMagellanic Cloud. We find none, and therefore put limits on the contribution ofhigh mass objects to the Galactic dark matter. At 95% confidence level weexclude objects in the mass range 0.3 solar masses to 30.0 solar masses fromcontributing more than 4 times 10^11 solar masses to the Galactic halo.Combined with earlier results, this means that objects with masses under 30solar masses cannot make up the entire dark matter halo if the halo is oftypical size. For a typical dark halo, objects with masses under 10 solarmasses contribute less than 40% of the dark matter.