Can MACHOs Probe the Shape of the Galaxy Halo?

Abstract

We study the prospects for the current microlensing searches, which have recently discovered several candidates, to yield useful information about the flattening of the Galaxy dark matter halo. Models of HI warps and N-body simulations of galaxy formation suggest that disks commonly form in oblate halos with a tilt between the disk and halo symmetry axes. The microlensing optical depth for the Large Magellanic Cloud depends sensitively on the disk-halo tilt angle in the Milky Way. We conclude that a much larger spread in values for $\tau (LMC)$ is consistent with rotation curve constraints than previously thought, and that the ratio $\tau (SMC)/\tau (LMC)$ of the optical depth to the Small and Large Magellanic clouds is not a clean test of halo flattening.

9 pages plain TeX, 4 figs. by FAX, Fermilab-Pub-93/391-A

Cited by in corpus (9)

• The Local Halo Density
• First detection of a gravitational microlensing candidate towards the Small Magellanic Cloud
• Microlensing
• Perturbation theory with dispersion and higher cumulants: framework and linear theory
• Searching for Machos (and other Dark Matter Candidates) in a Simulated Galaxy
• The Minimum Total Mass of MACHOs and Halo Models of the Galaxy
• Flattened Galactic Haloes and Baryonic Dark Matter
• The Galactic Halo from Microlensing
• Expected EAGLE event rate towards the Magellanic Clouds