Ω_B and Ω_0 from MACHOs and Local Group Dynamics

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Date

1999-09-10

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American Astronomical Society

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Abstract

We obtain restrictions on the universal baryon fraction, f_B ≡ Ω_B/Ω_0, by assuming that the observed microlensing events toward 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 f_B > 0.29^+0.18_-0.15. Consistency with the predictions of primordial nucleosynthesis leads to the further constraint on the total mass density, Ω_0 ~< 0.2.

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cosmology: theory, dark matter, gravitational lensing, Local Group, Magellanic Clouds

Citation

G. Steigman and I. Tkachev, "Ω_B and Ω_0 from MACHOs and Local Group Dynamics," The Astrophysical Journal 522, no. 2 (1999), doi:10.1086/307657