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ガンマ線によって明らかにされた銀河円盤におけるポジトンの非対称的な分布
Georg Weidenspointner1, Gerry Skinner, Pierre Jean
1Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, BP 44346, Toulouse Cedex 4, France. Georg.Weidenspointner@hll.mpg.de
Nature
|January 11, 2008
まとめ
511 keVのガンマ線放射を引き起こすポジトンの起源が特定されました. 非対称な放射は,外来的な暗黒物質ではなく,硬質の低質量X線バイナリ (LMXBs) が支配的な源で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
- 高エネルギー天文学 高エネルギー天文学
- 素粒子物理学 素粒子物理学について
背景:
- 電子・ポジトロン・アニヒライレーションは511 keVのガンマ線放射を発生させ,数十年にわたって銀河の中心から観測されています.
- これらのポジトンの正確な起源は,天体物理学における未解決の謎のままである.
- 提案された源には,恒星の核合成,コンパクトな物体,暗黒物質の消滅が含まれます.
研究 の 目的:
- 銀河系内部の511 keVのガンマ線放射に起因するポジトンの起源を調査する.
- ガンマ線放射の観測された不対称性が,既知の天体物理学的情報源と相関するかどうかを判断する.
- 主要なポジトロン源として,低質量X線バイナリ (LMXB) の貢献を評価する.
主な方法:
- 銀河盤内部の511 keVのガンマ線放射の空間分布の分析.
- 観測されたガンマ線非対称性を,ハードの低質量X線バイナリ (LMXBs) の分布と比較.
- LMXBからポジトロン脱出と消滅率をモデリングする.
主要な成果:
- 銀河の内部円盤 (銀河の中心から10~50度) からの511 keVの線放射に明らかな非対称性が検出されました.
- この非対称性は,硬質のLMXB (光子エネルギー放出>20 keVを持つもの) の分布と密接に一致しています.
- この発見は,硬質のLMXBがポジトンの支配的な源である可能性が高いことを示唆しており,脱出率は1秒あたり約10^41です.
結論:
- 低質量X線バイナリは,銀河系におけるポジトンの主要な源として強く示されています.
- この天体物理学的な説明は,暗黒物質の消滅のような異質な源の必要性を減らす.
- この研究は,ポジトンがLMXBから脱出し,星間媒介で消滅し,観測された狭い511 keVの線を生成することを確認しています.
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