Interferometric Visibility and Closure Phase of Microlensing Events with Finite Source Size

Abstract

Interferometers from the ground and space will be able to resolve the two images in a microlensing event. This will at least partially lift the inherent degeneracy between physical parameters in microlensing events. To increase the signal-to-noise ratio, intrinsically bright events with large magnifications will be preferentially selected as targets. These events may be influenced by finite source size effects both photometrically and astrometrically. Using observed finite source size events as examples, we show that the fringe visibility can be affected by 5% - 10%, and the closure phase by a few degrees: readily detectable by ground and space interferometers. Such detections will offer unique information about the lens-source trajectory relative to the baseline of the interferometers. Combined with photometric finite source size effects, interferometry offers a way to measure the angular sizes of the source and the Einstein radius accurately. Limb-darkening changes the visibility by a small amount compared with a source with uniform surface brightness, marginally detectable with ground-based instruments. We discuss the implications of our results for the plans to make interferometric observations of future microlensing events.

18 pages, 9 figures, submitted to MNRAS

References in corpus (9)

• First Results from the CHARA Array. II. A Description of the Instrument
• OGLE-2003-BLG-262: Finite-Source Effects from a Point-Mass Lens
• First microlens mass measurement: PLANET photometry of EROS BLG-2000-5
• OGLE-2003-BLG-238: Microlensing Mass Estimate of an Isolated Star
• Resolving gravitational microlensing events with long-baseline optical interferometry. Prospects for the ESO Very Large Telescope Interferometer
• Probing the atmosphere of a solar-like star by galactic microlensing at high magnification
• Spatial/Spectral Resolution of a Galactic Bulge K3 Giant Stellar Atmosphere via Gravitational Microlensing
• Determination of stellar shape in microlensing event MOA 2002-BLG-33
• Bringing closure to microlensing mass measurement

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