ブラックホールを検出器として用いた暗黒エネルギー観測～天体観測で宇宙複屈折を測定する新手法～

2026-01-28 東京大学

CMB の光と天体の光が受ける宇宙複屈折による回転の概念図（Credit: Naokawa, higgstan.com）

＜関連情報＞

• https://www.s.u-tokyo.ac.jp/ja/press/11052/
• https://journals.aps.org/prl/abstract/10.1103/srfg-9fdy

電波銀河を用いた宇宙複屈折トモグラフィーのユニバーサルプロファイル Universal Profile for Cosmic Birefringence Tomography with Radio Galaxies

Fumihiro Naokawa
Physical Review Letters  Published: 27 January, 2026
DOI: https://doi.org/10.1103/srfg-9fdy

Abstract

We propose a new method to tomographically probe cosmic birefringence using radio galaxies. We show that the redshift evolution of the cosmic birefringence angle induced by a slow-rolling pseudoscalar field, which is a candidate for dynamical dark energy, is independent of the detailed model of the pseudoscalar field. This universal profile evolves predominantly at z≲10. In contrast, if the origin is a dark matter-like pseudoscalar field, the resulting birefringence angle tends to be negligible in the low-redshift regime. This new insight provides a strong motivation to independently test the cosmic birefringence using polarized astrophysical sources such as radio galaxies. We find that a sample size of ⁢10⁵–10⁶ is required to distinguish the profiles, which is within the scope of ongoing and upcoming radio surveys such as ASKAP or SKA.