The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge
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 deg ^2 between −5° < l < 10° and −7° < b < −1°. In the central region with ∣ l ∣ < 5...
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2025-01-01
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| author | Kansuke Nunota Takahiro Sumi Naoki Koshimoto Nicholas J. Rattenbury Fumio Abe Richard Barry David P. Bennett Aparna Bhattacharya Akihiko Fukui Ryusei Hamada Shunya Hamada Naoto Hamasaki Yuki Hirao Stela Ishitani Silva Yoshitaka Itow Yutaka Matsubara Shota Miyazaki Yasushi Muraki Tsutsumi Nagai Greg Olmschenk Clement Ranc Yuki K. Satoh Daisuke Suzuki Paul. J. Tristram Aikaterini Vandorou Hibiki Yama (MOA collaboration) |
| author_facet | Kansuke Nunota Takahiro Sumi Naoki Koshimoto Nicholas J. Rattenbury Fumio Abe Richard Barry David P. Bennett Aparna Bhattacharya Akihiko Fukui Ryusei Hamada Shunya Hamada Naoto Hamasaki Yuki Hirao Stela Ishitani Silva Yoshitaka Itow Yutaka Matsubara Shota Miyazaki Yasushi Muraki Tsutsumi Nagai Greg Olmschenk Clement Ranc Yuki K. Satoh Daisuke Suzuki Paul. J. Tristram Aikaterini Vandorou Hibiki Yama (MOA collaboration) |
| author_sort | Kansuke Nunota |
| collection | DOAJ |
| description | 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 deg ^2 between −5° < l < 10° and −7° < b < −1°. In the central region with ∣ l ∣ < 5°, we estimate an optical depth of $\tau =[1.75\pm 0.04]\times 1{0}^{-6}\exp [(0.34\pm 0.02)({3}^{\circ }-| b| )]$ and an event rate of Γ = [16.08 ± 0.28] × 10 ^−6 $\exp [(0.44\pm 0.02)({3}^{\circ }-| b| )]{\mathrm{star}}^{-1}\,{\mathrm{yr}}^{-1}$ using a sample consisting of 3525 microlensing events, with Einstein radius crossing times of t _E < 760 days and a source star magnitude of I _s < 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. |
| format | Article |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-b9f91236b8bd4d84a9cf8bfa155dc4962025-02-05T14:13:26ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01979212310.3847/1538-4357/ada352The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic BulgeKansuke Nunota0https://orcid.org/0009-0005-3414-455XTakahiro Sumi1Naoki Koshimoto2Nicholas J. Rattenbury3Fumio Abe4Richard Barry5David P. Bennett6Aparna Bhattacharya7Akihiko Fukui8Ryusei Hamada9Shunya Hamada10Naoto Hamasaki11Yuki Hirao12Stela Ishitani Silva13Yoshitaka Itow14Yutaka Matsubara15Shota Miyazaki16Yasushi Muraki17Tsutsumi Nagai18Greg Olmschenk19Clement Ranc20Yuki K. Satoh21Daisuke Suzuki22Paul. J. Tristram23Aikaterini Vandorou24Hibiki Yama25(MOA collaboration)Department of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanDepartment of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanDepartment of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanDepartment of Physics, University of Auckland , Private Bag 92019, Auckland, New ZealandInstitute for Space-Earth Environmental Research, Nagoya University , Nagoya 464-8601, JapanCode 667, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USACode 667, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Department of Astronomy, University of Maryland , College Park, MD 20742, USACode 667, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Department of Astronomy, University of Maryland , College Park, MD 20742, USADepartment of Earth and Planetary Science, Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Instituto de Astrofisica de Canarias , Via Lactea s/n, E-38205 La Laguna, Tenerife, SpainDepartment of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanDepartment of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanDepartment of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanInstitute of Astronomy, Graduate School of Science, The University of Tokyo , 2-21-1 Osawa, Mitaka, Tokyo 181-0015, JapanCode 667, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Department of Physics, The Catholic University of America , Washington, DC 20064, USAInstitute for Space-Earth Environmental Research, Nagoya University , Nagoya 464-8601, JapanInstitute for Space-Earth Environmental Research, Nagoya University , Nagoya 464-8601, JapanInstitute of Space and Astronautical Science , Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210, JapanInstitute for Space-Earth Environmental Research, Nagoya University , Nagoya 464-8601, JapanDepartment of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanCode 667, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USASorbonne Université , CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, FranceCollege of Science and Engineering, Kanto Gakuin University , 1-50-1 Mutsuurahigashi, Kanazawa-ku, Yokohama, Kanagawa 236-8501, JapanDepartment of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanUniversity of Canterbury Mt. , John Observatory, P.O. Box 56, Lake Tekapo 8770, New ZealandCode 667, NASA Goddard Space Flight Center , Greenbelt, MD 20771, USA; Department of Astronomy, University of Maryland , College Park, MD 20742, USADepartment of Earth and Space Science, Graduate School of Science, Osaka University , Toyonaka, Osaka 560-0043, JapanWe 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 deg ^2 between −5° < l < 10° and −7° < b < −1°. In the central region with ∣ l ∣ < 5°, we estimate an optical depth of $\tau =[1.75\pm 0.04]\times 1{0}^{-6}\exp [(0.34\pm 0.02)({3}^{\circ }-| b| )]$ and an event rate of Γ = [16.08 ± 0.28] × 10 ^−6 $\exp [(0.44\pm 0.02)({3}^{\circ }-| b| )]{\mathrm{star}}^{-1}\,{\mathrm{yr}}^{-1}$ using a sample consisting of 3525 microlensing events, with Einstein radius crossing times of t _E < 760 days and a source star magnitude of I _s < 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.https://doi.org/10.3847/1538-4357/ada352Galactic centerMilky Way GalaxyMicrolensing event rateMicrolensing optical depthGravitational microlensing |
| spellingShingle | Kansuke Nunota Takahiro Sumi Naoki Koshimoto Nicholas J. Rattenbury Fumio Abe Richard Barry David P. Bennett Aparna Bhattacharya Akihiko Fukui Ryusei Hamada Shunya Hamada Naoto Hamasaki Yuki Hirao Stela Ishitani Silva Yoshitaka Itow Yutaka Matsubara Shota Miyazaki Yasushi Muraki Tsutsumi Nagai Greg Olmschenk Clement Ranc Yuki K. Satoh Daisuke Suzuki Paul. J. Tristram Aikaterini Vandorou Hibiki Yama (MOA collaboration) The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge The Astrophysical Journal Galactic center Milky Way Galaxy Microlensing event rate Microlensing optical depth Gravitational microlensing |
| title | The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge |
| title_full | The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge |
| title_fullStr | The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge |
| title_full_unstemmed | The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge |
| title_short | The Microlensing Event Rate and Optical Depth from MOA-II 9 Yr Survey Toward the Galactic Bulge |
| title_sort | microlensing event rate and optical depth from moa ii 9 yr survey toward the galactic bulge |
| topic | Galactic center Milky Way Galaxy Microlensing event rate Microlensing optical depth Gravitational microlensing |
| url | https://doi.org/10.3847/1538-4357/ada352 |
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