OmegaB and Omega0 From MACHOs and Local Group Dynamics
Abstract
We obtain restrictions on the universal baryon fraction, fB = OmegaB/Omega0, by assuming that the observed microlensing events towards the Large Magellanic Cloud are due to baryonic MACHOs in the halo of the Galaxy and by extracting a bound to the total mass of the Milky Way from the motion of tracer galaxies in the Local Group. We find a lower bound fB > 0.29+0.18-0.15. Consistency with the predictions of primordial nucleosynthesis leads to the further constraint on the total mass density, Omega0 < 0.2.
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