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アンドロメダIIの2つの矮星銀河の合併の残骸である
N C Amorisco1, N W Evans2, G van de Ven3
1Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark.
Nature
|February 28, 2014
まとめ
天文学者は,矮星銀河アンドロメダIIで恒星流を検出し,2つの小さな銀河の合併の証拠を明らかにしました. この発見は,銀河の合併が非常に低い恒星質量でも起こり,スケールフリー銀河形成理論を支持することを示しています.
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:
- 巨大な銀河は,階層的な合併と増殖によって成長します.
- 巨大な銀河のハローの星流は,増殖の証拠を提供します.
- 低質量銀河の合併は予測されているが,109太陽質量以下ではまだ観測されていない.
研究 の 目的:
- 低質量の恒星で銀河の形成と合併過程を調査する.
- 矮星銀河の合併の証拠を探すために.
- 最も低い質量スケールまで銀河形成のスケールフリーな性質をテストするために.
主な方法:
- 矮小の球状銀河アンドロメダIIの内側にある恒星流の運動検出.
- 星の流れの性質を分析して,その起源を推測する.
- 残存銀河の回転のダイナミック評価.
主要な成果:
- 太陽の質量10^7の矮星銀河であるアンドロメダIIで動力学的に星の流れが検出されました.
- 流れの性質は,2つの矮星銀河の合併の残骸であることを示している.
- この合併は,アンドロメダ2号の動態に大きな影響を及ぼし,その主要な軸の回転を引き起こした.
結論:
- この研究は,恒星の質量が太陽の質量10^7ほど低い銀河の合併の最初の直接的な証拠を提供します.
- この発見は,銀河形成がスケールフリーなプロセスであり,最小の銀河スケールにまで適用できるという理論を支持する.
- 観測された合併イベントは,矮星銀河の残骸のダイナミクスに大きな影響を与えました.
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