Colour Change Measurements of Gravitational Microlensing Events by Using the Difference Image Analysis Method

Abstract

Detecting colour changes of a gravitational microlensing event induced by the limb-darkened extended source effect is important to obtain useful information both about the lens and source star. However, precise measurements of the colour changes are hampered by blending, which also causes colour changes of the event. In this paper, we show that although the colour change measured from the subtracted image by using the recently developed photometric method of the ``difference image analysis'' (DIA) differs from the colour change measured by using the conventional method based on the extraction of the individual source stars' point spread functions, the curve of the colour changes (colour curve) constructed by using the DIA method enables one to obtain the same information about the lens and source star, but with significantly reduced uncertainties due to the absence of blending. We investigate the patterns of the DIA colour curves for both single lens and binary lens events by constructing colour change maps.

total 8 pages, including 4 figures and no table, MNRAS, in press

References in corpus (4)

• Detecting Stellar Spots by Gravitational Microlensing
• Difference Image Analysis of Galactic Microlensing I. Data Analysis
• Difference Image Analysis of Galactic Microlensing II. Microlensing Events
• Chromaticity of Gravitational Microlensing Events

Cited by in corpus (6)

• Extended-Source Effect and Chromaticity in Two-Point-Mass Microlensing
• WeCAPP - The Wendelstein Calar Alto Pixellensing Project I Tracing Dark and Bright Matter in M31
• On the possibility of an astronomical detection of chromaticity effects in microlensing by wormhole-like objects
• Microlensing of strongly interacting binary systems
• Variation of the stellar color in high-magnification and caustic-crossing microlensing events
• MEDEA: a real time imaging pipeline for pixel lensing