Kinematic outliers in the Large Magellanic Cloud: constraints on star-star microlensing

Although a decade of microlensing searches towards the Large Magellanic Cloud (LMC) has detected 13-25 possible microlensing events, the nature and the location of the lenses, being either halo MACHOs or LMC stars, remains a subject of debate. The star-star lensing models generically predict the existence of a small population (more than similar to5 per cent) of stars with a spatial and kinematic distribution different from the thin, young disc of the LMC. Here we present the results of a large spectroscopic survey of the LMC, consisting of more than 1300 radial velocities measured accurately with the 2dF instrument. In this large sample, no evidence is found for any extraneous population over the expected LMC and Galactic components. Any additional, kinematically distinct, population can only be present at less than the 1 per cent level. We discuss the significance of this finding for the LMC self-lensing models.