A systematic fitting scheme for caustic-crossing microlensing events

We outline a method for fitting binary-lens caustic-crossing microlensing events based on the alternative model parametrization proposed and detailed by Cassan. As an illustration of our methodology, we present an analysis of OGLE-2007-BLG-472, a double-peaked Galactic microlensing event with a sour...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2009-05, Vol.395 (2), p.787-796
Main Authors: Kains, N., Cassan, A., Horne, K., Albrow, M. D., Dieters, S., Fouqué, P., Greenhill, J., Udalski, A., Zub, M., Bennett, D. P., Dominik, M., Donatowicz, J., Kubas, D., Tsapras, Y., Anguita, T., Batista, V., Beaulieu, J.-P., Brillant, S., Bode, M., Bramich, D. M., Burgdorf, M., Caldwell, J. A. R., Cook, K. H., Coutures, Ch, Dominis Prester, D., Jørgensen, U. G., Kane, S., Marquette, J. B., Martin, R., Menzies, J., Pollard, K. R., Rattenbury, N., Sahu, K. C., Snodgrass, C., Steele, I., Vinter, C., Wambsganss, J., Williams, A., Kubiak, M., Pietrzyński, G., Soszyński, I., Szewczyk, O., Szymański, M. K., Ulaczyk, K., Wyrzykowski, Ł.
Format: Article
Language:English
Subjects:
Alternatives
Astronomy
Astrophysics
binaries: general
Earth, ocean, space
Exact sciences and technology
Galactic Astrophysics
Galaxy: bulge
gravitational lensing
Markov analysis
methods: miscellaneous
planetary systems
Research methodology
Sciences of the Universe
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Summary:We outline a method for fitting binary-lens caustic-crossing microlensing events based on the alternative model parametrization proposed and detailed by Cassan. As an illustration of our methodology, we present an analysis of OGLE-2007-BLG-472, a double-peaked Galactic microlensing event with a source crossing the whole caustic structure in less than three days. In order to identify all possible models we conduct an extensive search of the parameter space, followed by a refinement of the parameters with a Markov Chain Monte Carlo algorithm. We find a number of low-χ2 regions in the parameter space, which lead to several distinct competitive best models. We examine the parameters for each of them, and estimate their physical properties. We find that our fitting strategy locates several minima that are difficult to find with other modelling strategies and is therefore a more appropriate method to fit this type of event.
ISSN:0035-8711
1365-2966
DOI:10.1111/j.1365-2966.2009.14615.x