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Title: New method to measure proper motions of microlensed sources: Application to candidate free-floating-planet event MOA-2011-BLG-262

We develop a new method to measure source proper motions in microlensing events, which can partially overcome problems due to blending. It takes advantage of the fact that the source position is known precisely from the microlensing event itself. We apply this method to the event MOA-2011-BLG-262, which has a short timescale t {sub E} = 3.8 day, a companion mass ratio q = 4.7 × 10{sup –3}, and a very high or high lens-source relative proper motion μ{sub rel} = 20 mas yr{sup –1} or 12 mas yr{sup –1} (for two possible models). These three characteristics imply that the lens could be a brown dwarf or a massive planet with a roughly Earth-mass 'moon'. The probability of such an interpretation would be greatly increased if it could be shown that the high lens-source relative proper motion was primarily due to the lens rather than the source. Based on the long-term monitoring data of the Galactic bulge from the Optical Gravitational Lensing Experiment, we measure the source proper motion that is small, μ{sub s}=(−2.3,−0.9)±(2.8,2.6) mas yr{sup −1} in a (north, east) Galactic coordinate frame. These values are then important input into a Bayesian analysis of the event presented in amore » companion paper by Bennett et al.« less
Authors:
 [1] ;  [2] ; ;  [1] ;
  1. Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland)
  2. (United States)
Publication Date:
OSTI Identifier:
22357056
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 785; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; GALAXIES; GRAVITATIONAL LENSES; MASS; MOON; ORBITS; PLANETS; PROBABILITY; PROPER MOTION