銀河中心付近の磁場の下限は50マイクロガウスである
Roland M Crocker1, David I Jones, Fulvio Melia
1School of Physics, Monash University, Victoria 3110, Australia. Roland.Crocker@mpi-hd.mpg.de
Nature
|January 8, 2010
まとめ
銀河の中心近くの磁場は,400パーセック (pc) のスケールで少なくとも50マイクロガウス (microG) です. この発見は,数十年にわたる不確実性を解決し,銀河の内部に高度に集中した磁気エネルギー密度があることを示唆しています.
科学分野:
- 天体物理学 天体物理学
- 銀河のダイナミクス
- プラズマ物理学 プラズマ物理学
背景:
- 銀河の中心付近の磁場強さは,数十年にわたって2桁の大きさで不確実である.
- 以前の推定値は,様々なスケール (100〜400パーセック,PC) で6〜1,000マイクロガウス (マイクロG) であった.
- これらの不確実性は,圧力均衡,均等分割,および観測による解釈に関する異なる仮定から生じました.
研究 の 目的:
- 銀河の中心付近の磁場振幅の長年の不確実性を解決するために.
- 以前のデータとスペクトル解析を集めて磁場強度を制限する.
- 銀河内のエネルギー密度と分布に対する磁場強度の影響を決定する.
主な方法:
- 銀河中心の非熱的なラジオスペクトルに関する以前のデータの収集と分析.
- 宇宙線電子の冷却に起因する下向きのスペクトル断絶の識別 (シンクロトロンへのブレーム放射).
- ガンマ線放射限度およびスペクトル断裂特性に基づいて磁場強度を制限するためのモデリング.
主要な成果:
- 非熱的なラジオスペクトルの下向きの断絶が確認されました.
- このスペクトル断裂は,400パーセック (pc) のスケールで少なくとも50マイクロガウス (microG) の銀河中心の磁場を必要とします.
- さらに考慮すると,磁場強度は約100マイクロGで,磁気エネルギーの濃度がかなり高いことが示唆される.
結論:
- 銀河の中心付近の磁場は,特定の仮定に基づいて以前から推論されたものよりもかなり強い.
- 銀河の磁気エネルギーの10%以上は,小さな部分 (約. 全体の0.05%) を占めている.
- この発見は,銀河中心の恒星間媒介と磁場に関するモデルの重要な制約を提示する.
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