February 5, 1998 CfA Colloquium

Title: Searching for Dark Matter with Gravitational Microlensing: A Report from the MACHO Collaboration

Speaker: Christopher Stubbs

Abstract: Understanding the nature and distribution of the dark matter are among the most pressing outstanding open questions in the physical sciences. Our team has conducted a search for the dark matter in the Milky Way by exploiting gravitational microlensing: If the dark matter halo of our Galaxy is made of MAssive Compact Halo Objects (MACHOs), then occasionally one of these will pass close to the line of sight to a distant star. This alignment produces a dynamic gravitational lensing system, the signature of which is an apparent transient brightening of the background star. We have now detected more than 200 instances of gravitational microlensing. I will describe the status of the project, the results and their implications, and plans for future projects.

Reference for students:Ann Rev of Astron & Astrophysics, vol 34, pg 419; Jean Collins will have copies.