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Abstract
A comprehensive new approach is presented for deriving probability densities of physical properties characterizing the lens and source that constitute an observed galactic microlensing event. While previously encountered problems are overcome, constraints from event anomalies and model parameter uncertainties can be incorporated into the estimates. Probability densities for given events need to be carefully distinguished from the statistical distribution of the same parameters among the underlying population from which the actual lenses and sources are drawn. Using given model distributions of the mass spectrum, the mass density, and the velocity distribution of Galactic disc and bulge constituents, probability densities of lens mass, distance, and the effective lenssource velocities are derived, where the effect on the distribution that arises from additional observations of annual parallax or finitesource effects, or the absence of significant effects, is shown. The presented formalism can also be used to calculate probabilities for the lens to belong to one or another population and to estimate parameters that characterize anomalies. Finally, it is shown how detection efficiency maps for binarylens companions in the physical parameters, such as companion mass and orbital semimajor axis, arise from values determined for the mass ratio and dimensionless projected separation parameter, including the deprojection of the orbital motion for elliptical orbits. Compared to the naive estimate based on 'typical values', the detection efficiency for lowmass companions is increased by mixing in higher detection efficiencies for smaller mass ratios (i.e. smaller masses of the primary).
Original language  English 

Pages (fromto)  669692 
Number of pages  24 
Journal  Monthly Notices of the Royal Astronomical Society 
Volume  367 
Issue number  2 
DOIs  
Publication status  Published  1 Apr 2006 
Keywords
 gravitational lensing
 methods : statistical
 binaries : general
 planetary systems
 Galaxy : stellar content
 PLANETARY COMPANIONS
 EXTRASOLAR PLANETS
 HIGH MAGNIFICATION
 MAGELLANICCLOUD
 MASS
 CONSTRAINTS
 LIMITS
 PHOTOMETRY
 ABUNDANCE
 STELLAR
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 1 Finished

Astrophysics at St Andrews: Astrophysics at St.Andrews
Cameron, A. C. (PI) & Horne, K. D. (CoI)
1/04/06 → 31/03/11
Project: Standard