OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event

Cheongho Han , Ian A. Bond , Andrzej Udalski , Andrew Gould , Valerio Bozza , Yuki Hirao , Arnaud Cassan (1) , Michael D. Albrow , Sun-Ju Chung , Kyu-Ha Hwang , Chung-Uk Lee , Yoon-Hyun Ryu , In-Gu Shin , Yossi Shvartzvald , Jennifer C. Yee , Youn Kil Jung , Doeon Kim , Woong-Tae Kim , Sang-Mok Cha , Dong-Jin Kim , Hyoun-Woo Kim , Seung-Lee Kim , Dong-Joo Lee , Yongseok Lee , Byeong-Gon Park , Richard W. Pogge , Weicheng Zang , Fumio Abe , Richard Barry , David P. Bennett , Aparna Bhattacharya , Martin Donachie , Akihiko Fukui , 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 , Przemek Mróz , Michał K. Szymański , Jan Skowron , Radek Poleski , Igor Soszyński , Paweł Pietrukowicz , Szymon Kozłowski , Krzysztof Ulaczyk , Krzysztof A. Rybicki , Patryk Iwanek , Marcin Wrona , Charles A. Beichman , Geoffery Bryden , Sean Carey , B. Scott Gaudi , Calen B. Henderson

1 IAP - Institut d'Astrophysique de Paris

In this work, we present the analysis of the binary microlensing event OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense and continuous coverage with the high-quality photometry data from ground-based observations combined with the space-based Spitzer observations of this long timescale event enables us to uniquely determine the masses M ₁ = 0.40 ± 0.05 M _⊙ and M ₂ = 0.13 ± 0.01 M _⊙ of the individual lens components. Because the lens-source relative parallax and the vector lens-source relative proper motion are unambiguously determined, we can likewise unambiguously predict the astrometric offset between the light centroid of the magnified images (as observed by the Gaia satellite) and the true position of the source. This prediction can be tested when the individual-epoch Gaia astrometric measurements are released.

Keywords: binaries: general; gravitational lensing: micro; Astrophysics - Solar and Stellar Astrophysics

Domains: Sciences of the Universe [physics]

Cheongho Han, Ian A. Bond, Andrzej Udalski, Andrew Gould, Valerio Bozza, et al.. OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event. The Astrophysical Journal, 2019, 876, ⟨10.3847/1538-4357/ab1539⟩. ⟨insu-03747934⟩