| Microlensing towards the Small Magellanic Cloud EROS 2: first year survey (2007) | |||||||||||||
Abstract | |||||||||||||
| . We present here an analysis of the light curves of 5.3 million stars in the Small Magellanic Cloud observed by EROS (Exp'erience de Recherche d'Objets Sombres). One star exhibits a variation that is best interpreted as due to gravitational microlensing by an unseen object. This candidate was also reported by the MACHO collaboration. Once corrected for blending, the Einstein radius crossing time is 123 days, corresponding to lensing by a Halo object of 2:6 +8:2 \Gamma2:3 M fi . The maximum magnification is a factor of 2.6. The light curve also displays a periodic modulation with a 2.5% amplitude and a period of 5.1 days. Parallax analysis of the candidate indicates that a Halo lens would need to have a mass of at least 0:3 M fi , although a lens in the SMC could have a mass as low as 0:07 M fi . We estimate the optical depth for microlensing towards the SMC due to this event to be ΒΈ 3:3\Theta10 \Gamma7 , with an uncertainty dominated by Poisson statistics. We show that this optica... | |||||||||||||
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