銀河形成のピーク10億年前にバリオンが強く支配された円盤銀河
R Genzel1,2, N M Förster Schreiber1, H Übler1
1Max-Planck-Institut für extraterrestrische Physik (MPE), Giessenbachstrasse 1, 85748 Garching, Germany.
Nature
|March 17, 2017
まとめ
初期の大量銀河はバリオンが多く 局所銀河よりも暗黒物質が少ない この研究は外部の円盤の回転速度が減っていることを明らかにし 標準的なダークマターのモデルに 挑戦しています
科学分野:
- 宇宙学
- 銀河の形成 と 進化
- 天体物理学
背景:
- 冷たい暗黒物質 (CDM) の宇宙論は,銀河が暗黒物質のハロに埋め込まれていると仮定する.
- ローカルな銀河の回転曲線は半径で一定の速度または増加速度を示し,CDMをサポートします.
- 以前の研究では 初期の銀河のバリオンの分数が高かったが ダークマターの質量については 結論が出なかった.
研究 の 目的:
- 巨大な恒星形成銀河の 外部円盤の回転曲線を調査する
- 初期の宇宙における 標準的な冷たい暗黒物質モデルの予測を テストするためです
- 初期の銀河の形成における バリオンとダークマターの役割を理解するために
主な方法:
- 6つの巨大な恒星形成銀河の回転曲線 (回転速度対円盤半径) の観測.
- 回転速度から推論された動的質量の分析.
- 推論された動的質量と恒星とガス質量の推定値の比較.
主要な成果:
- 高赤偏移の銀河の外盤の回転速度は半径が増加するにつれて減少することが判明した.
- この傾向は,大規模な初期の銀河の 重要なバリオン支配を示唆しています
- 観測された減少は,局所宇宙と比較して初期の宇宙で暗黒物質の濃度が低いことを示しています.
結論:
- 初期の宇宙の巨大な銀河は,これまで考えられていたよりもバリオンが多く存在していた.
- 高赤偏移の銀河盤は,大きな速度分散のためにかなりの圧力期間を経験しました.
- バリオンは宇宙初期に 暗黒物質のハロの中心に 効率的に凝縮されました
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