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arXiv · 1805.09350

OGLE-2014-BLG-0962 and the First Statistical Validation of Bayesian Priors for Galactic Microlensing

Yutong Shan·Jennifer C. Yee·Andrzej Udalski·Ian A. Bond·Yossi Shvartzvald·In-Gu Shin·Youn-Kil Jung·Sebastiano Calchi Novati·Charles A. Beichman·Sean Carey·B. Scott Gaudi·Andrew Gould·Richard W. Pogge·Radosław Poleski·Jan Skowron·Szymon Kozłowski·Przemysław Mróz·Paweł Pietrukowicz·Michał K. Szymański·Igor Soszyński·Krzysztof Ulaczyk·Łukasz Wyrzykowski·Fumio Abe·Richard K. Barry·David P. Bennett·Aparna Bhattacharya·Martin Donachie·Akihiko Fukui·Yuki Hirao·Yoshitaka Itow·Kohei Kawasaki·Iona Kondo·Naoki Koshimoto·Man Cheung Alex Li·Yutaka Matsubara·Yasushi Muraki·Shota Miyazaki·Masayuki Nagakane·Clément Ranc·Nicholas J. Rattenbury·Haruno Suematsu·Denis J. Sullivan·Takahiro Sumi·Daisuke Suzuki·Paul J. Tristram·Atsunori Yonehara·Dan Maoz·Shai Kaspi·Matan Friedmann
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Abstract

OGLE-2014-BLG-0962 (OB140962) is a stellar binary microlensing event that was well-covered by observations from the Spitzer satellite as well as ground-based surveys. Modelling yields a unique physical solution: a mid-M+M-dwarf binary with $M_{\rm prim} = 0.20 \pm 0.01 M_\odot$ and $M_{\rm sec} = 0.16 \pm 0.01 M_\odot$, with projected separation of $2.0 \pm 0.3$ AU. The lens is only $D_{\rm LS} = 0.41 \pm 0.06$ kpc in front of the source, making OB140962 a bulge lens and the most distant Spitzer binary lens to date. In contrast, because the Einstein radius ($\theta_{\rm E} = 0.143 \pm 0.007$ mas) is unusually small, a standard Bayesian analysis, conducted in the absence of parallax information, would predict a brown dwarf binary. We test the accuracy of Bayesian analysis over a set of Spitzer lenses, finding overall good agreement throughout the sample. We also illustrate the methodology for probing the Galactic distribution of planets by comparing the cumulative distance distribution of the Spitzer 2-body lenses to that of the Spitzer single lenses.

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Yutong Shan, Jennifer C. Yee, Andrzej Udalski, Ian A. Bond, Yossi Shvartzvald, In-Gu Shin, Youn-Kil Jung, Sebastiano Calchi Novati, Charles A. Beichman, Sean Carey, B. Scott Gaudi, Andrew Gould, Richard W. Pogge, Radosław Poleski, Jan Skowron, Szymon Kozłowski, Przemysław Mróz, Paweł Pietrukowicz, Michał K. Szymański, Igor Soszyński, Krzysztof Ulaczyk, Łukasz Wyrzykowski, Fumio Abe, Richard K. Barry, David P. Bennett, Aparna Bhattacharya, Martin Donachie, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Kohei Kawasaki, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Masayuki Nagakane, Clément Ranc, Nicholas J. Rattenbury, Haruno Suematsu, Denis J. Sullivan, Takahiro Sumi, Daisuke Suzuki, Paul J. Tristram, Atsunori Yonehara, Dan Maoz, Shai Kaspi, Matan Friedmann. 2018-05-23. OGLE-2014-BLG-0962 and the First Statistical Validation of Bayesian Priors for Galactic Microlensing. https://arxiv.org/abs/1805.09350

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