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Astron. Astrophys. 344, L63-L66 (1999)


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Letter to the Editor

Microlensing towards the Small Magellanic Cloud EROS 2 two-year analysis *

C. Afonso 1, C. Alard 9, J.N. Albert 2, J. Andersen 6, R. Ansari 2, É. Aubourg 1, P. Bareyre 1,4, F. Bauer 1,4, J.P. Beaulieu 5, A. Bouquet 4, S. Char 7, X. Charlot 1, F. Couchot 2, C. Coutures 1, F. Derue 2, R. Ferlet 5, J.F. Glicenstein 1, B. Goldman 1, A. Gould **  1,8, D. Graff 8, M. Gros 1, J. Haissinski 2, J.C. Hamilton 4, D. Hardin 1, J. deKat 1, A. Kim 4, T. Lasserre 1, É. Lesquoy 1, C. Loup 5, C. Magneville 1, B. Mansoux 2, J.B. Marquette 5, É. Maurice 3, A. Milsztajn 1, M. Moniez 2, N. Palanque-Delabrouille 1, O. Perdereau 2, L. Prévot 3, N. Regnault 2, J. Rich 1, M. Spiro 1, A. Vidal-Madjar 5, L. Vigroux 1 and S. Zylberajch The EROS collaboration 1

1 CEA, DSM, DAPNIA, Centre d'Études de Saclay, F-91191 Gif-sur-Yvette Cedex, France
2 Laboratoire de l'Accélérateur Linéaire, IN2P3 CNRS, Université Paris-Sud, F-91405 Orsay Cedex, France
3 Observatoire de Marseille, 2 pl. Le Verrier, F-13248 Marseille Cedex 04, France
4 Collège de France, Physique Corpusculaire et Cosmologie, IN2P3 CNRS, 11 pl. M. Berthelot, F-75231 Paris Cedex, France
5 Institut d'Astrophysique de Paris, INSU CNRS, 98 bis Boulevard Arago, F-75014 Paris, France
6 Astronomical Observatory, Copenhagen University, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
7 Universidad de la Serena, Facultad de Ciencias, Departamento de Fisica, Casilla 554, La Serena, Chile
8 Departments of Astronomy and Physics, Ohio State University, Columbus, OH 43210, USA
9 DASGAL, 77 avenue de l'Observatoire, F-75014 Paris, France

Received 10 December 1998 / Accepted 9 March 1999

Abstract

We present the analysis of the first two years of a search for microlensing of stars in the Small Magellanic Cloud with the EROS (Expérience de Recherche d'Objets Sombres) project. A single event is detected, already present in the first year analysis. This low event rate allows us to put new constraints on the fraction of the Galactic Halo mass due to compact objects in the mass range [[FORMULA], 1][FORMULA]. These limits, along with the fact that the two SMC events observed so far are probably due to SMC deflectors, suggest that LMC and SMC self-lensing may dominate the event rate.

Key words: Galaxy: halo – Galaxy: kinematics and dynamics – Galaxy: stellar content – cosmology: dark matter – cosmology: gravitational lensing

* Based on observations made at the European Southern Observatory, La Silla, Chile.
** Alfred P. Sloan Foundation Fellow

Send offprint requests to: Nathalie.Delabrouille@cea.fr

© European Southern Observatory (ESO) 1999

Online publication: March 29, 1999

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