ブラックホールの周囲を渦巻く磁場を天文学者がとらえる(Astronomers capture magnetic fields twirling around black hole)

2024-03-28

2024-03-27 アリゾナ大学

新しいイメージは、アリゾナ大学の研究者や望遠鏡が参加するイベントホライズンテレスコープコラボレーションによって明らかにされ、超大質量ブラックホールSagittarius A*またはSgr A*の縁から螺旋状に広がる強力で整然とした磁場を明らかにしました。この新しい視点は、天の川銀河の中心に潜むモンスターの姿を初めて偏光光で見たもので、M87銀河の中心にあるM87*というはるかに大きなブラックホールと類似した磁場構造を明らかにしました。これは、強力な磁場がすべてのブラックホールに共通する可能性を示唆しています。この類似性はまた、Sgr A*に隠れたジェットの存在を示唆しています。これらの結果は、3月27日にThe Astrophysical Journal Lettersで発表されました。

＜関連情報＞

射手座A事象の地平線望遠鏡の最初の結果。VII. リングの偏光 First Sagittarius A Event Horizon Telescope Results. VII. Polarization of the Ring

The Event Horizon Telescope Collaboration (See the end matter for the full list of authors.)The Event Horizon Telescope Collaboration, Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach,＋
The Astrophysical Journal Letters Published:2024 March 27
DOI:10.3847/2041-8213/ad2df0

Abstract

The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A* (Sgr A*), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ± 2.3 μas and modest azimuthal brightness asymmetry, consistent with the expected appearance of a black hole with mass M ≈ 4 × 10⁶M_⊙. From these observations, we present the first resolved linear and circular polarimetric images of Sgr A*. The linear polarization images demonstrate that the emission ring is highly polarized, exhibiting a prominent spiral electric vector polarization angle pattern with a peak fractional polarization of ∼40% in the western portion of the ring. The circular polarization images feature a modestly (∼5%–10%) polarized dipole structure along the emission ring, with negative circular polarization in the western region and positive circular polarization in the eastern region, although our methods exhibit stronger disagreement than for linear polarization. We analyze the data using multiple independent imaging and modeling methods, each of which is validated using a standardized suite of synthetic data sets. While the detailed spatial distribution of the linear polarization along the ring remains uncertain owing to the intrinsic variability of the source, the spiraling polarization structure is robust to methodological choices. The degree and orientation of the linear polarization provide stringent constraints for the black hole and its surrounding magnetic fields, which we discuss in an accompanying publication.