M I C R O L E N S I N G  E X P L O R A T I O N

of  the

G A L A X Y  &  A N D R O M E D A

People Publications Overview Internal

Recent observations of microlensing events towards the LMC pose a variety of interesting questions. However, observation of only a handful of events along a single line of sight limits our ability to extract useful information about the Galactic distribution of the lenses. The MEGA collaboration is an attempt to circumvent these difficulties by observing microlensing towards the Andromeda Galaxy using difference image photometry.

If galactic halos have substantial baryonic components expected event rates for M31 microlensing observations are perhaps ten times higher than for the LMC. Most of these lenses probably reside in M31 itself. Additionally, the extent of the disk of M31 allows us to probe diverse lines of sight through the M31 halo and thus determine the distribution of its microlensing matter more accurately.

Beyond microlensing, difference image photometry is an exciting fast-developing field in its own right. The MEGA collaboration has three major goals:

  1. Determination of the Structure of Galactic Halos.
  2. An Inventory of Variable Star Populations in M31.
  3. Development of the Difference Image Photometry technique.

This research is supported by several grants by the NSF and STScI, and formerly by a David and Lucile Packard Foundation Fellowship.

Send comments to: arlin@astro.columbia.edu

Last updated: 15 July 1999