The Effect of Tidal Stripping on Composite Stellar Populations in Dwarf Spheroidal Galaxies

The Effect of Tidal Stripping on Composite Stellar Populations in Dwarf Spheroidal Galaxies
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潮汐剥离对矮椭球星系复合星族的影响

DOI：
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发表时间：
2009
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影响因子：
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通讯作者：
G. Battaglia
G. Battaglia
中科院分区：
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文献类型：
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作者：
L. Sales;A. Helmi;G. Battaglia

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我们使用N体模拟来研究潮汐对类银河系卫星星系运动结构的影响 潜力。在这里，我们关注的是一颗球形暗物质占主导地位的卫星的演化，该卫星由两个恒星分量模拟而成 设置从头开始在空间和运动学上分离，以类似于贫金属者和富金属者的配置 本地群中几个矮小球体中的恒星种群。我们发现，初始差异的一个重要衰减是 这两个恒星分量的分布发生在近心半径较小的轨道上。这主要是由于(I) 潮汐剥离后暗物质分量所提供的引力支持的丧失和(Ii)潮汐优先发生 影响更大的恒星分量，导致其速度色散的净减少，作为对质量损失的响应，这 从而缩小了运动学间隙。我们将这些想法应用于雕塑者和船底矮球。它们在轨道上的差异可能 这有助于解释为什么在前一颗恒星中，贫金属星和富金属星之间存在明显的运动学分离，而在船底座 这种隔离要微妙得多。
We use N-body simulations to study the effects of tides on the kinematical structure of satellite galaxies orbiting a Milky Way-like potential. Here we focus on the evolution of a spherical, dark matter dominated satellite, which is modelled with two stellar components set ab initio to be spatially and kinematically segregated, in a way that resembles the configuration of the metal poor and metal rich stellar populations in several dwarf spheroidals of the Local Group. We find that an important attenuation of the initial differences in the distribution of the two stellar components occurs for orbits with small pericentric radii. This is mainly due to (i) the loss of the gravitational support provided by the dark matter component after tidal stripping takes place and (ii) tides preferentially affect the more extended stellar component, leading to a net decrease in its velocity dispersion as a response for the mass loss, which thus shrinks the kinematical gap. We apply these ideas to the Sculptor and Carina dwarf spheroidals. Differences in their orbits might help to explain why in the former a clear kinematical separation between metal poor and metal rich stars is apparent, while in Carina this segregation is significantly more subtle.