| タイトル | The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge |
| DOI | https://doi.org/10.3847/1538-4357/ada352 |
| 本文（外部サイト） | https://ir.library.osaka-u.ac.jp/repo/ouka/all/101061/AstrophysJ_979_2.pdf |
| 著者（英） | 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 |
| 発行日 | 2025-02-01 |
| 発行機関など | Institute of Physics |
| 刊行物名 | Astrophysical Journal |
| 巻 | 979 |
| 号 | 2 |
| 開始ページ | 123 |
| 言語 | eng |
| 内容記述 | Nunota K., Sumi T., Koshimoto N., et al. The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge. Astrophysical Journal 979, 123 (2025); https://doi.org/10.3847/1538-4357/ada352.
We present measurements of the microlensing optical depth and event rate toward the Galactic bulge using the data set from the 2006 to 2014 MOA-II survey, which covers 22 bulge fields spanning ∼42 deg2 between −5° < l < 10° and −7° < b < −1°. In the central region with ∣l∣ < 5°, we estimate an optical depth of τ = [ 1.75 ± 0.04 ] × 1 0 − 6 exp [ ( 0.34 ± 0.02 ) ( 3 ∘ − ∣ b ∣ ) ] and an event rate of Γ = [16.08 ± 0.28] × 10−6 exp [ ( 0.44 ± 0.02 ) ( 3 ∘ − ∣ b ∣ ) ] star − 1 yr − 1 using a sample consisting of 3525 microlensing events, with Einstein radius crossing times of tE < 760 days and a source star magnitude of Is < 21.4 mag. We confirm our results are consistent with the latest measurements from the OGLE-IV 8 yr data set. We find our result is inconsistent with a prediction based on Galactic models, especially in the central region with ∣b∣ < 3°. These results can be used to improve the Galactic bulge model, and more central regions can be further elucidated by upcoming microlensing experiments, such as the PRime-focus Infrared Microlensing Experiment and Nancy Grace Roman Space Telescope. |
| 権利 | This article is licensed under a Creative Commons Attribution 4.0 International License. |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/1322003 |
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