The Microlensing Event Rate and Optical Depth from MOA-II 9 year Survey toward the Galactic Bulge
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2024
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| author | Nunota, Kansuke Sumi, Takahiro Koshimoto, Naoki Rattenbury, Nicholas J. Abe, Fumio Barry, Richard Bennett, David P. Bhattacharya, Aparna Fukui, Akihiko Hamada, Ryusei Hamada, Shunya Hamasaki, Naoto Hirao, Yuki Silva, Stela Ishitani Itow, Yoshitaka Matsubara, Yutaka Miyazaki, Shota Muraki, Yasushi Nagai, Tsutsumi Olmschenk, Greg Ranc, Clement Satoh, Yuki K. Suzuki, Daisuke Tristram, Paul J. Vandorou, Aikaterini Yama, Hibiki |
| author_facet | Nunota, Kansuke Sumi, Takahiro Koshimoto, Naoki Rattenbury, Nicholas J. Abe, Fumio Barry, Richard Bennett, David P. Bhattacharya, Aparna Fukui, Akihiko Hamada, Ryusei Hamada, Shunya Hamasaki, Naoto Hirao, Yuki Silva, Stela Ishitani Itow, Yoshitaka Matsubara, Yutaka Miyazaki, Shota Muraki, Yasushi Nagai, Tsutsumi Olmschenk, Greg Ranc, Clement Satoh, Yuki K. Suzuki, Daisuke Tristram, Paul J. Vandorou, Aikaterini Yama, Hibiki |
| contents | We present measurements of the microlensing optical depth and event rate toward the Galactic bulge using the dataset from the 2006--2014 MOA-II survey, which covers 22 bulge fields spanning ~42 deg^2 between -5 deg < l < 10 deg and -7 deg < b < -1 deg. In the central region with |l|<5 deg, we estimate an optical depth of τ = [1.75+-0.04]*10^-6exp[(0.34+-0.02)(3 deg-|b|)] and an event rate of Γ = [16.08+-0.28]*10^-6exp[(0.44+-0.02)(3 deg-|b|)] star^-1 year^-1 using a sample consisting of 3525 microlensing events, with Einstein radius crossing times of tE < 760 days and source star magnitude of IsWe confirm our results are consistent with the latest measurements from OGLE-IV 8 year dataset (Mróz et al. 2019). We find our result is inconsistent with a prediction based on Galactic models, especially in the central region with |b|<3 deg. These results can be used to improve the Galactic bulge model, and more central regions can be further elucidated by future microlensing experiments, such as The PRime-focus Infrared Microlensing Experiment (PRIME) and Nancy Grace Roman Space Telescope. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_23553 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The Microlensing Event Rate and Optical Depth from MOA-II 9 year Survey toward the Galactic Bulge Nunota, Kansuke Sumi, Takahiro Koshimoto, Naoki Rattenbury, Nicholas J. Abe, Fumio Barry, Richard Bennett, David P. Bhattacharya, Aparna Fukui, Akihiko Hamada, Ryusei Hamada, Shunya Hamasaki, Naoto Hirao, Yuki Silva, Stela Ishitani Itow, Yoshitaka Matsubara, Yutaka Miyazaki, Shota Muraki, Yasushi Nagai, Tsutsumi Olmschenk, Greg Ranc, Clement Satoh, Yuki K. Suzuki, Daisuke Tristram, Paul J. Vandorou, Aikaterini Yama, Hibiki Astrophysics of Galaxies We present measurements of the microlensing optical depth and event rate toward the Galactic bulge using the dataset from the 2006--2014 MOA-II survey, which covers 22 bulge fields spanning ~42 deg^2 between -5 deg < l < 10 deg and -7 deg < b < -1 deg. In the central region with |l|<5 deg, we estimate an optical depth of τ = [1.75+-0.04]*10^-6exp[(0.34+-0.02)(3 deg-|b|)] and an event rate of Γ = [16.08+-0.28]*10^-6exp[(0.44+-0.02)(3 deg-|b|)] star^-1 year^-1 using a sample consisting of 3525 microlensing events, with Einstein radius crossing times of tE < 760 days and source star magnitude of IsWe confirm our results are consistent with the latest measurements from OGLE-IV 8 year dataset (Mróz et al. 2019). We find our result is inconsistent with a prediction based on Galactic models, especially in the central region with |b|<3 deg. These results can be used to improve the Galactic bulge model, and more central regions can be further elucidated by future microlensing experiments, such as The PRime-focus Infrared Microlensing Experiment (PRIME) and Nancy Grace Roman Space Telescope. |
| title | The Microlensing Event Rate and Optical Depth from MOA-II 9 year Survey toward the Galactic Bulge |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2410.23553 |