论文标题
暗物质光环旋转的随机步行模型
A random-walk model for dark matter halo spins
论文作者
论文摘要
我们扩展了Vitvitska等人的随机步行模型。从其合并历史中预测暗物质光环的旋转。使用更新的合并速率，轨道参数分布和N体约束，我们表明，当我们在N-Body模拟中测量的旋转参数的分布可以准确地重现，当我们包括Halos的旋转与次数subhalos的角度之间的弱相关性时。我们进一步表明，该模型与根据N体模拟确定的随时间旋转幅度的相关性近似一致，而它略微低估了从同一模拟测得的自旋矢量方向上的相关性。该模型可用于预测从非N体源得出的合并历史记录中的旋转，从而规避了非常高分辨率模拟的需求，以允许对自旋进行准确的测量。它可能与建模系统特别相关，这些模型系统会随着时间的推移积累晕孔的角动量（例如银河盘） - 我们表明，使用半乳糖半分析星系形成模型计算出的银河盘尺寸的分布的小而显着变化。
We extend the random-walk model of Vitvitska et al. for predicting the spins of dark matter halos from their merger histories. Using updated merger rates, orbital parameter distributions, and N-body constraints we show that this model can accurately reproduce the distribution of spin parameters measured in N-body simulations when we include a weak correlation between the spins of halos and the angular momenta of infalling subhalos. We further show that this model is in approximate agreement with the correlation of the spin magnitude over time as determined from N-body simulations, while it slightly underpredicts the correlation in the direction of the spin vector measured from the same simulations. This model is useful for predicting spins from merger histories derived from non-N-body sources, thereby circumventing the need for very high resolution simulations to permit accurate measurements of spins. It may be particularly relevant to modeling systems which accumulate angular momentum from halos over time (such as galactic discs) - we show that this model makes small but significant changes in the distribution of galactic disc sizes computed using the Galacticus semi-analytic galaxy formation model.
