Iras-allsky

OGLE-2014-BLG-0962 and a Comparison of Galactic Model Priors to Microlensing Data

March 2019 • 2019ApJ...873...30S

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

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. Modeling yields a unique physical solution: a mid-M+M-dwarf binary with M prim = 0.20 ± 0.01 M and M sec = 0.16 ± 0.01 M , with projected separation of 2.0 ± 0.3 au. The lens is only D LS = 0.41 ± 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 (θ E = 0.143 ± 0.007 mas) is unusually small, a standard Bayesian analysis, conducted in the absence of parallax information, would predict a brown dwarf binary. We compare the results of Bayesian analysis using two commonly used Galactic model priors to the measured values for a set of Spitzer lenses. We find all models tested predict lens properties consistent with the Spitzer data. Furthermore, we illustrate the methodology for probing the Galactic distribution of planets by comparing the cumulative distance distribution of the Spitzer two-body lenses to that of the Spitzer single lenses.

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Sebastiano Calchi Novati

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Sean Carey

Senior Scientist