EROS 2 proper motion survey: Constraints on the halo white dwarfs

Abstract

We are conducting a 377°2 proper motion survey in the ∼V and I bands in order to determine the cool white dwarf contribution to the Galactic dark matter. Using the 250°2 for which we possess three epochs, and applying selection criteria designed to isolate halo-type objects, we find no candidates in a 5500 pc3 effective volume for old, fast MV = 17 white dwarfs. We check the detection efficiency by cross-matching our catalogue with Luyten's NLTT catalogue. The halo white dwarf contribution cannot exceed 5% (95% C.L.) for objects with MV = 17 and 1 ≤ V - I ≤ 1.5. The same conclusion applies to a 14 Gyr halo composed of white dwarfs with hydrogen atmosphere, as modeled by Chabrier.