Bulge microlensing optical depth from EROS 2 observations $^{\bullet}$

Abstract

We present a measurement of the microlensing optical depth toward the Galactic bulge based on the analysis of 15 contiguous fields centered on and containing clump-giant stars (belonging to the extended clump area) monitored during almost three bulge seasons by EROS (Expérience de Recherche d'Objets Sombres). We find averaged over all fields, based on 16 microlensing events with clump giants as sources. This value is substantially below several other determinations by the MACHO and OGLE groups and is more in agreement with what is expected from axisymmetric and non-axisymmetric bulge models.