Local Group dwarf galaxies: nature and nurture
Local Group dwarf galaxies: nature and nurture
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本星系群矮星系：自然与培育
DOI：
10.1111/j.1365-2966.2011.20181.x
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发表时间：
2011
影响因子：
4.8
通讯作者：
S. White
中科院分区：
文献类型：
--
作者：
Till Sawala;C. Scannapieco;S. White
我们在一个银河系大小的晕及其环境的高分辨率流体动力学宇宙学模拟中研究了矮星系的形成和演化。我们的模拟包括气体冷却、恒星形成、超新星反馈、金属浓缩和紫外线加热。在模拟中总共形成了90颗卫星和400多个孤立的矮星系，使人们能够系统地研究决定它们演化的内部和环境过程。我们发现，95%的卫星星系在z=0时是无气体的，并确定了气体损失的三种机制：超新星反馈、潮汐剥离和再电离导致的光蒸发。只有总质量在∼5×109M⊙以上的富含气体的卫星星系才能被发现。相比之下，对于孤立的矮星系，总质量为∼109M⊙构成了一个急剧的转变；质量较小的星系在z=0时主要是无气体的，质量较大的孤立的矮星系通常能够保留它们的气体。总的来说，我们发现矮小星系的总质量是决定其恒星形成、金属丰度和气体含量的主要因素，但这种剥离可能解释了观测到的总质量接近109M⊙的场矮星系和卫星间气体含量的差异。我们还发现，通过潮汐剥离暗物质浓度低于恒星的发光矮小星系的形态变化，不能解释暗矮星球状星系的高总质量光比。
We investigate the formation and evolution of dwarf galaxies in a high-resolution, hydrodynamical cosmological simulation of a Milky Way sized halo and its environment. Our simulation includes gas cooling, star formation, supernova feedback, metal enrichment and ultraviolet heating. In total, 90 satellites and more than 400 isolated dwarf galaxies are formed in the simulation, allowing a systematic study of the internal and environmental processes that determine their evolution. We find that 95 per cent of satellite galaxies are gas free at z= 0, and identify three mechanisms for gas loss: supernova feedback, tidal stripping and photoevaporation due to re-ionization. Gas-rich satellite galaxies are only found with total masses above ∼5 × 109 M⊙. In contrast, for isolated dwarf galaxies, a total mass of ∼109 M⊙ constitutes a sharp transition; less massive galaxies are predominantly gas free at z= 0, more massive, isolated dwarf galaxies are often able to retain their gas. In general, we find that the total mass of a dwarf galaxy is the main factor which determines its star formation, metal enrichment and its gas content, but that stripping may explain the observed difference in gas content between field dwarf galaxies and satellites with total masses close to 109 M⊙. We also find that a morphological transformation via tidal stripping of infalling, luminous dwarf galaxies whose dark matter is less concentrated than their stars cannot explain the high total mass-to-light ratios of the faint dwarf spheroidal galaxies.