The POINT-AGAPE survey: 4 high signal-to-noise microlensing candidates detected towards M31

S. Paulin-Henriksson (1) , P. Baillon , A. Bouquet (1) , B.J. Carr , M. Creze (1) , N.W. Evans , Y. Giraud-Heraud (1) , A. Gould (1) , P. Hewett , J. Kaplan (1) , E. Kerins , Y. Le Du (1) , A.L. Melchior (2) , S.J. Smartt , D. Valls-Gabaud (3)

1 PCC - Physique Corpusculaire et Cosmologie - Collège de France
2 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
3 LATT - Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées

We have carried out a survey of the Andromeda galaxy for unresolved microlensing (pixel lensing). We present a subset of four short timescale, high signal-to-noise microlensing candidates found by imposing severe selection criteria: the source flux variation exceeds the flux of an R=21 magnitude star and the full width at half maximum timescale is less than 25 days. Remarkably, in three out of four cases, we have been able to measure or strongly constrain the Einstein crossing time of the event. One event, which lies projected on the M31 bulge, is almost certainly due to a stellar lens in the bulge of M31. The other three candidates can be explained either by stars in M31 and M32 or by MACHOs.

Mots clés: galaxies: halo; galaxies: individual: M 31; gravitational lensing; dark matter

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]

S. Paulin-Henriksson, P. Baillon, A. Bouquet, B.J. Carr, M. Creze, et al.. The POINT-AGAPE survey: 4 high signal-to-noise microlensing candidates detected towards M31. Astronomy and Astrophysics - A&A, 2003, 405, pp.15-21. ⟨10.1051/0004-6361:20030519⟩. ⟨in2p3-00013663⟩