The POINT-AGAPE Microlensing Survey: First Constraint on MACHOs towards M31

To reveal the galactic dark matter in the form of MACHOs (“Massive Astrophysical Compact Halo Objects”), the POINT-AGAPE collaboration is carrying out a search for gravitational microlensing towards M31. A clear microlensing signal is detected. The high-threshold analysis of 3-year data leads to 7 bright and short microlensing candidates. The preliminary estimation of the detection efficiency implies that less than 25% (60%) of standard halos can be composed of objects with masses between 10^{-4} and 10^{-1} (10^{-1} and 1) solar mass at the 95% C.L. This result is compatible with previous microlensing results towards the Magellanic Clouds and gives the first constraints on MACHOs for a distant spiral galaxy.