The Possibility of Detecting Planets in the Andromeda Galaxy

The Angstrom Project is using a global network of 2m-class telescopes toconduct a high cadence pixel microlensing survey of the bulge of the AndromedaGalaxy (M31), with the primary aim of constraining its underlying bulge massdistribution and stellar mass function. Here we investigate the feasibility ofusing such a survey to detect planets in M31. We estimate the efficiency ofdetecting signals for events induced by planetary systems as a function ofplanet/star mass ratio and separation, source type and background M31 surfacebrightness. We find that for planets of a Jupiter-mass or above that are withinthe lensing zone (~1 -3 AU) detection is possible above 3 $\sigma$, withdetection efficiencies ~3% for events associated with giant stars, which arethe typical source stars of pixel-lensing surveys. A dramatic improvement inthe efficiency of ~40 -- 60% is expected if follow-up observations on an 8mtelescope are made possible by a real-time alert system.Comment: total 8 pages, including 8 figures, ApJ, submitte