Kinematic outliers in the LMC: constraints on star-star microlensing

Abstract

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 about 5 percent 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 distint, population can only be present at less than the 1 percent level. We discuss the significance of this finding for the LMC self-lensing models.

arXiv commentMNRAS accepted, to be published 2003. 6pp w/ 10 eps fig, references updated to match proof

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• The Chemical Enrichment History of the Large Magellanic Cloud
• Metallicities, Age--Metallicity relationships, and Kinematics of Red Giant Branch Stars in the Outer Disk of the Large Magellanic Cloud
• The Case of the Off-Center, Levitating Bar in the Large Magellanic Cloud
• Tagging the Chemical Evolution History of the Large Magellanic Cloud Disk
• JWST-TST Proper Motions: I. High-Precision NIRISS Calibration and Large Magellanic Cloud Kinematics
• The Magellanic Edges Survey I. Description and First Results
• Kinematical Structure of the Magellanic System
• A homogeneous comparison between the chemical composition of the Large Magellanic Cloud and the Sagittarius dwarf galaxy
• Evidence of a counterrotating core in the Large Magellanic Cloud
• Identification of the Microlens in Event MACHO-LMC-20
• An Expanded Chemo-dynamical Sample of Red Giants in the Bar of the Large Magellanic Cloud
• Microlensing towards the Magellanic Clouds and M31: is the quest for MACHOs still open?