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若き宇宙における古い銀河
A Cimatti1, E Daddi, A Renzini
1INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125, Firenze, Italy. cimatti@arcetri.astro.it
Nature
|July 9, 2004
まとめ
地元の宇宙にとって極めて重要な巨大な球形銀河は,予想よりもずっと早く形成されました. この研究は,銀河の進化の現在のモデルに挑戦し,遠く,完全に組み立てられた巨大な銀河を特定します.
科学分野:
- 天文学と天体物理学について
- 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
背景:
- 巨大な球形銀河は,局所宇宙の恒星の半分以上を占め,古い恒星集団と最小限の恒星形成を特徴としています.
- 現在のモデルは,これらの銀河が階層的な合併によって遅れて形成されると示唆しているが,その形成のタイムラインと初期の出現は不明のままである.
研究 の 目的:
- 巨大な球状銀河の形成のタイムラインを調査する.
- 初期の出現が,進化の効果によるものなのか,観察の限界によるものなのかを判断する.
主な方法:
- 銀河の特性を確認するために,光譜分析を行います.
- 銀河の構造を評価するための形態学的識別.
- 高赤偏移 (1.6 < z < 1.9) の銀河の観測.
主要な成果:
- 4つの古い,完全に組み立てられた,巨大な (10 ^ 11 太陽の質量) 球形銀河の識別.
- これらの銀河は赤偏移 (z ~ 1.6-1.9) で発見され,宇宙は現在の年齢の約四分の一しかなかった.
- これは,このような巨大で成熟した銀河がこれまでに最も遠くから検出されたことを表しています.
結論:
- 初期のタイプの巨大な銀河は,理論的なシミュレーションによって予測されたよりも,初期の宇宙ではるかに速く組み立てられました.
- この発見は,階層的な銀河形成の既存のモデルに異議を唱えている.
- 初期の宇宙における巨大な銀河の形成のためのより急速な進化の経路を示唆しています.
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