Dark matter haloes within clusters
Dark matter haloes within clusters
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DOI：
10.1046/j.1365-8711.1998.01918.x
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发表时间：
1998-01
影响因子：
4.8
通讯作者：
S. Ghigna;B. Moore;F. Governato;G. Lake;T. Quinn;J. Stadel
中科院分区：
文献类型：
--
作者：
S. Ghigna;B. Moore;F. Governato;G. Lake;T. Quinn;J. Stadel
我们研究的性质，暗物质晕内的丰富的星系团使用高分辨率的模拟，捕捉宇宙学背景下的冷暗物质宇宙。质量和力的分辨率允许在2 Mpc的星系团维里半径（哈勃常数H 0 = 50 km s−1 Mpc−1）内分辨出150个圆速度大于80 km s−1的晕。这使得对在致密环境中演化的大样本暗物质晕的统计特性进行前所未有的研究成为可能。附着在这些晕上的累积质量分数从200千秒差距处的接近0%到维里半径处的13%不等。即使在这个分辨率下，过度合并的问题仍然存在;在星团中心100-200 kpc范围内通过的晕被潮汐破坏。额外的子结构在早期的大规模祖先晕中丢失。远心半径与近心半径的中位数比为6：1，因此轨道分布接近各向同性，圆形轨道很少见，径向轨道很常见。晕的轨道相对于星系团内的位置和平滑暗物质背景的轨道都是无偏的，并且没有检测到速度偏差。使用应用于其轨道近中心的简单分析预测，幸存光环的潮汐半径通常很好地拟合。团簇内的卤素浓度高于田间的浓度。在星系团内部，晕的密度分布可以被潮汐力和个别与其他晕的相遇所改变，从而导致显著的质量损失--“星系骚扰”。晕之间的合并不会发生在星系团维里半径内。
We examine the properties of dark matter haloes within a rich galaxy cluster using a high-resolution simulation that captures the cosmological context of a cold dark matter universe. The mass and force resolution permit the resolution of 150 haloes with circular velocities larger than 80 km s−1 within the cluster virial radius of 2 Mpc (with Hubble constant H0 = 50 km s−1 Mpc−1). This enables an unprecedented study of the statistical properties of a large sample of dark matter haloes evolving in a dense environment. The cumulative fraction of mass attached to these haloes varies from close to zero per cent at 200 kpc to 13 per cent at the virial radius. Even at this resolution the overmerging problem persists; haloes that pass within 100–200 kpc of the cluster centre are tidally disrupted. Additional substructure is lost at earlier epochs within the massive progenitor haloes. The median ratio of apocentric to pericentric radii is 6:1, so that the orbital distribution is close to isotropic, circular orbits are rare and radial orbits are common. The orbits of haloes are unbiased with respect to both position within the cluster and the orbits of the smooth dark matter background, and no velocity bias is detected. The tidal radii of surviving haloes are generally well-fitted using the simple analytic prediction applied to their orbital pericentres. Haloes within clusters have higher concentrations than those in the field. Within the cluster, halo density profiles can be modified by tidal forces and individual encounters with other haloes that cause significant mass loss —‘galaxy harassment’. Mergers between haloes do not occur inside the cluster virial radius.