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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2604.09875 |
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| _version_ | 1866917410419769344 |
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| author | Chiba, Masashi Wyse, Rosemary F. G. Kirby, Evan N. Cohen, Judith G. Dobos, László Gerasimov, Roman Ishigaki, Miho N. Hayashi, Kohei Filion, Carrie Arnaboldi, Magda Bhattacharya, Souradeep Hirai, Yutaka Kobayashi, Chiaki Komiyama, Yutaka Kuzma, Pete B. Ogami, Itsuki Chies-Santos, Ana L. Klock-Miranda, Nicole L. Sestito, Federico Budavári, Tamás Cooper, Andrew P. Ding, Keyi Escala, Ivanna Ferreira, Elisa G. M. Gerhard, Ortwin Henderson, Lauren Hong, Jihye Horigome, Shunichi Ikeda, Ryota Ishikawa, Ryo Kirihara, Takanobu Li, Zhuohan Martin, Nicolas Okamoto, Rin Miyazaki Sakurako Pattnaik, Rohan Sato, Kyosuke Suzuki, Yoshihisa Szalay, Alexander S. Wardana, Dafa Wei, Viska Wu, Wenbo Wu, Zhenyu Xu, Xinfeng Ye, Xianhao Miki, Yohei Zhang, Xiangwei Zhao, Gang Zhao, Jingkun Zhao, Xiaosheng |
| author_facet | Chiba, Masashi Wyse, Rosemary F. G. Kirby, Evan N. Cohen, Judith G. Dobos, László Gerasimov, Roman Ishigaki, Miho N. Hayashi, Kohei Filion, Carrie Arnaboldi, Magda Bhattacharya, Souradeep Hirai, Yutaka Kobayashi, Chiaki Komiyama, Yutaka Kuzma, Pete B. Ogami, Itsuki Chies-Santos, Ana L. Klock-Miranda, Nicole L. Sestito, Federico Budavári, Tamás Cooper, Andrew P. Ding, Keyi Escala, Ivanna Ferreira, Elisa G. M. Gerhard, Ortwin Henderson, Lauren Hong, Jihye Horigome, Shunichi Ikeda, Ryota Ishikawa, Ryo Kirihara, Takanobu Li, Zhuohan Martin, Nicolas Okamoto, Rin Miyazaki Sakurako Pattnaik, Rohan Sato, Kyosuke Suzuki, Yoshihisa Szalay, Alexander S. Wardana, Dafa Wei, Viska Wu, Wenbo Wu, Zhenyu Xu, Xinfeng Ye, Xianhao Miki, Yohei Zhang, Xiangwei Zhao, Gang Zhao, Jingkun Zhao, Xiaosheng |
| contents | The recently commissioned Subaru `Ōnohi`ula Prime Focus Spectrograph (PFS) will obtain spectra from nearly 2,400 fibers that cover 1.24 square degrees. The 360 night Subaru Strategic Program for PFS is dedicating approximately one-third of its allocation (130 nights) to study the structure and evolution of galaxies in the Local Group. This Galactic Archaeological survey has three pillars. (1) We will determine whether the mass density profiles of dwarf galaxies are consistent with cusps, as expected for cold dark matter, or cores, as expected from alternative dark matter theories or baryonic feedback. We will deduce the density profiles as a function of radius from modeling of the full line-of-sight velocity and abundance distributions for six dwarf galaxies. Our total sample will consist of 18,000 member stars to beyond the nominal tidal radius of each system. (2) From measurements of the [alpha/Fe] abundance ratio, we will learn the difference in assembly history of the two most massive galaxies in the Local Group: M31 and the Milky Way. We will observe 30,000 member stars over 45 square degrees of M31's halo and outer disk. (3) We will uncover how the most fragile (outer) part of the Milky Way responded to accretion events both in the distant past (such as Gaia-Sausage Enceladus) and in more recent history (such as the Sagittarius dwarf spheroidal galaxy). To support this study, PFS will provide velocities and metallicities--from which, in combination with photometry, we will deduce ages--for tens of thousands of main-sequence stars out to a Galactocentric distance of ~30 kpc. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_09875 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Galactic Archaeology with the Subaru `Ōnohi`ula Prime Focus Spectrograph Strategic Program Chiba, Masashi Wyse, Rosemary F. G. Kirby, Evan N. Cohen, Judith G. Dobos, László Gerasimov, Roman Ishigaki, Miho N. Hayashi, Kohei Filion, Carrie Arnaboldi, Magda Bhattacharya, Souradeep Hirai, Yutaka Kobayashi, Chiaki Komiyama, Yutaka Kuzma, Pete B. Ogami, Itsuki Chies-Santos, Ana L. Klock-Miranda, Nicole L. Sestito, Federico Budavári, Tamás Cooper, Andrew P. Ding, Keyi Escala, Ivanna Ferreira, Elisa G. M. Gerhard, Ortwin Henderson, Lauren Hong, Jihye Horigome, Shunichi Ikeda, Ryota Ishikawa, Ryo Kirihara, Takanobu Li, Zhuohan Martin, Nicolas Okamoto, Rin Miyazaki Sakurako Pattnaik, Rohan Sato, Kyosuke Suzuki, Yoshihisa Szalay, Alexander S. Wardana, Dafa Wei, Viska Wu, Wenbo Wu, Zhenyu Xu, Xinfeng Ye, Xianhao Miki, Yohei Zhang, Xiangwei Zhao, Gang Zhao, Jingkun Zhao, Xiaosheng Astrophysics of Galaxies Solar and Stellar Astrophysics The recently commissioned Subaru `Ōnohi`ula Prime Focus Spectrograph (PFS) will obtain spectra from nearly 2,400 fibers that cover 1.24 square degrees. The 360 night Subaru Strategic Program for PFS is dedicating approximately one-third of its allocation (130 nights) to study the structure and evolution of galaxies in the Local Group. This Galactic Archaeological survey has three pillars. (1) We will determine whether the mass density profiles of dwarf galaxies are consistent with cusps, as expected for cold dark matter, or cores, as expected from alternative dark matter theories or baryonic feedback. We will deduce the density profiles as a function of radius from modeling of the full line-of-sight velocity and abundance distributions for six dwarf galaxies. Our total sample will consist of 18,000 member stars to beyond the nominal tidal radius of each system. (2) From measurements of the [alpha/Fe] abundance ratio, we will learn the difference in assembly history of the two most massive galaxies in the Local Group: M31 and the Milky Way. We will observe 30,000 member stars over 45 square degrees of M31's halo and outer disk. (3) We will uncover how the most fragile (outer) part of the Milky Way responded to accretion events both in the distant past (such as Gaia-Sausage Enceladus) and in more recent history (such as the Sagittarius dwarf spheroidal galaxy). To support this study, PFS will provide velocities and metallicities--from which, in combination with photometry, we will deduce ages--for tens of thousands of main-sequence stars out to a Galactocentric distance of ~30 kpc. |
| title | Galactic Archaeology with the Subaru `Ōnohi`ula Prime Focus Spectrograph Strategic Program |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2604.09875 |