パルサーのような極化角度の振動は,近くの急速なラジオバーストから発生する
Ryan Mckinven1,2, Mohit Bhardwaj3, Tarraneh Eftekhari4,5
1Department of Physics, McGill University, Montréal, Quebec, Canada. ryan.mckinven@mcgill.ca.
Nature
|January 1, 2025
まとめ
急速無線爆発 (FRB) は,磁気圏の起源を支持するユニークな偏振角の回転を示します. この発見は これらの謎の宇宙信号の ニュートロン星の祖先を 排除するのに役立ちます
科学分野:
- 天文学と天体物理学
- コスミック・ラジオ・トランシーント
背景:
- FRBは,銀河系外からの,数ミリ秒間の無線電波です.
- パルサーと類似していることから,中性子星の起源が示唆されているが,その放射機構と起源はほとんど不明である.
- パルサーとは異なり,FRBは通常,極化角度 (PA) の最小の変動を示し,存在すると,標準回転ベクトルモデル (RVM) から逸脱する.
研究 の 目的:
- FRB 20221022Aの極化特性を調べるため
- パルサーやマグネターのような 既知の天体と似ています
- 観測された極化行動に基づいて,FRBの放出モデルと原始型を制限する.
主な方法:
- カナダの水素濃度マッピング実験 (CHIME/FRB) プロジェクトを使用して,FRB 20221022Aの検出と局所化.
- 爆発期間中の線形偏向位置角度 (PA) の分析.
- 回転ベクトルモデル (RVM) を使用して観測されたPAの進化をモデル化します.
主要な成果:
- FRB 20221022Aは,約2.5ミリ秒の間に ~130°の PA 回転を示した.
- このPAの進化は,パルサーといくつかの電磁星で観測された特徴的なS形の曲線に非常に似ている.
- 観測されたPAの振る舞いは,磁気圏の放射モデルをサポートするRVMによってよく記述されています.
結論:
- FRB 20221022AのPA進化は磁気圏からの放射の起源を強く支持し,遠くからの衝撃を含むモデルを排除しています.
- 磁気圏モデルを補強する 繰り返し発生するFRBのテンポポリメトリック研究と一致しています
- RVMはデータに適合するが,特定のパラメータ (傾き,磁気傾き) は未決定であり,プロジェニタとして非常に短い周期のパルサーを除く.
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