銀河間媒介におけるイオン化されたヘリウムの構造を,遠紫外線スペクトロスコピクエクスプローラーで解明した
まとめ
初期の宇宙の構造は,中性水素 (H I) とイオン化されたヘリウム (He II) の吸収によって明らかになる. 観測により,He II ライマンアルファ吸収が示され,ほとんどの特徴にはH Iの対称性があり,低密度地域でも構造を示しています.
科学分野:
- 宇宙学と天体物理学について
- 初期の宇宙の研究 初期の宇宙の研究
- 銀河間媒介は銀河間媒介である.
背景:
- クワザールスペクトルは中性水素 (H I) とイオン化されたヘリウム (He II) の吸収を明らかにしています.
- これらの吸収特性は,初期の宇宙における宇宙の構造を検知する.
研究 の 目的:
- 初期の宇宙におけるHe II ライマンアルファ (ライアルファ) 吸収を分析するために.
- He II と H I コラムの密度間の関係を調査する.
- ヘリウムIIのイオン化に寄与する源を理解する.
主な方法:
- 遠紫外線光譜探査機 (FUSE) の観測を活用した.
- クワザール HE2347-4342のスペクトルを1000から1187アングストーム帯で分析した.
- レッドシフト2.3から2.7のHe II Lyalpha吸収線が解けました.
主要な成果:
- He II Lyalphaの吸収を分離された線の森として解決した.
- He II 機能の約 50% の H I 対応体が見つかりました.
- 観測されたHe IIからH Iのコラム密度比は,1から>1000の範囲で,平均約80でした.
- 特定されたHe II Lyalpha吸収器は,H Iの同位体がない.
結論:
- 観測されたHe IIとH I柱の密度比は,クエーサーによる光イオン化を示唆し,さらに,スターバースト銀河やフィルターされたクエーサー放射線からの貢献がある.
- H I の対称性のない He II 吸収器の存在は,低密度地域における構造を示しています.
- 発見は,重力不安定によって引き起こされる構造形成モデルと一致しています.
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