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宇宙再イオン化による矮星銀河形成の抑制
J Stuart B Wyithe1, Abraham Loeb
1University of Melbourne, Parkville, Victoria 3010, Australia. swyithe@physics.unimelb.edu.au
Nature
|May 20, 2006
まとめ
初期の宇宙の銀河は,再イオン化後に抑制された矮星銀河の形成を示しています. 再イオン化後の銀河は,太陽の10^10.9の最小質量を必要とし,宇宙の恒星形成率に影響を与えました.
科学分野:
- コスモロジー・コスモロジーとは
- 銀河の形成と進化について
- 初期の宇宙 天体物理学
背景:
- 最近の発見は,ビッグバンから最初の10億年以内に形成された多数の淡い銀河を明らかにしています.
- これらの初期の銀河分布の変動は,宇宙水素のイオン化分数に影響を与えた.
- 理論的なモデルは,宇宙再イオン化後の抑制された矮星銀河の形成を予測し,恒星形成の減少を引き起こしている.
研究 の 目的:
- 宇宙再イオン化後の矮星銀河形成の予測抑制に関する観測的証拠を提供するため.
- 赤道偏移 z ≈ 5.5.5 で電離放射線を放出する銀河の最小質量を決定する.
主な方法:
- 宇宙水素のイオン化分数の観測された散乱の分析,初期のクエーザーの視線に沿って.
- 観測された散乱と銀河の質量分布に基づく理論的予測の比較.
- 淡い,初期の銀河の最近の発見から得られたデータを活用して.
主要な成果:
- 宇宙再イオン化後の矮星銀河形成の抑制の証拠が報告されています.
- 赤道偏移 z ≈ 5.5 で最も電離放射線を寄与する銀河は,およそ 10^10.9 ± 0.5 太陽の質量を上回る質量を持っていたに違いない.
- この最小質量は,再イオン化が支配したと考えられている銀河の質量よりも (二次数) 大きく大きい.
結論:
- この発見は,再イオン化後の抑制された矮星銀河形成の理論的予測を裏付けている.
- より大規模な銀河の明確な集団が,再電離化後の電離放射線を支配した.
- 将来の赤外線望遠鏡の調査では,矮星銀河の抑制の前に最初の再イオン化に責任を持つより早い,より小さな銀河を特定することが期待されています.
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