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初期の宇宙における光学的に見えない巨大な銀河の支配的な集団
T Wang1,2,3, C Schreiber4,5,6, D Elbaz4
1Institute of Astronomy, Graduate School of Science, The University of Tokyo, Tokyo, Japan. twang.nju@gmail.com.
Nature
|August 9, 2019
まとめ
初期の宇宙の 巨大で塵に満ちた銀河は 見過ごされていました これらの新発見の銀河は,初期の宇宙の星形成の推定値を大幅に高め,現在の銀河形成モデルに挑戦しています.
科学分野:
- 宇宙の進化
- 銀河の形成と進化
- 初期の宇宙の天体物理学
背景:
- 赤道偏移 z > 3 の宇宙星形成の歴史は,主に紫外線で選択された銀河を用いて研究されている.
- 紫外線観測では,巨大で,塵が多く,または古い恒星群の銀河が不足しています.
- 以前の研究では 巨大な初期の銀河の集団ではなく 極端なスターバースト銀河が 特定されました
研究 の 目的:
- 初期の宇宙 (z > 3) の巨大な銀河の豊富さと星形成率の密度を調査する.
- 紫外線や赤外線で 覆われている巨大な銀河を 特定するためです
- 以前見逃した集団の性質と 宇宙への貢献を特徴づける
主な方法:
- 塵で覆われた銀河を検出するために 870マイクロメートルのサブミリメートル観測を行う.
- 紫外線から赤外線に近いスペクトル領域を分析し,遮蔽されていない銀河を特定します.
- 観測された銀河の宇宙密度と恒星形成率の推定.
主要な成果:
- 超紫外線から近赤外線で観測されていなかった 39の巨大な恒星系を検出した.
- これらの銀河の空間密度は 極端なスターバーストよりも2度高いのです
- 恒星形成の速度は年間 ~200 太陽質量で,初期の宇宙の恒星形成の速度の密度に大きく貢献しています.
結論:
- 巨大で塵に満ちた銀河は 初期の宇宙の 重要で過小評価されていた部分です
- 巨大な銀河の形成の現在のモデルに 挑戦しています
- これらの銀河は,現在の大規模な銀河団や群の祖先である可能性が高い.
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