利用弱引力透镜效应的尖峰和尺度-尺度相关统计区分暗能量模型

Discriminate Dark Energy Models with Statistics of Peak Counting and Scale-scale Correlation of the Weak Lensing Effect

为了研究不同宇宙学模型下弱引力透镜效应的性质,利用N-体模拟产生的数据,通过光线追踪技术,生成二维的κ样本.对应于不同的暗能量状态方程参数的模型,即w=-0.8,w=-1.0,w=-1.2,生成了3组样本.对于这些模型所生成的样本视场均为3°×3°,并假设所有作为背景源的星系都分布在z=1处的平面上.对这些κ场的样本均进行了尖峰统计和尺度-尺度相关的统计.对尖峰的统计结果显示,包含噪声的κ场中尖峰分布在不同模型下的差别还是存在的.噪声改变了中等幅值和小幅值的尖峰分布,而对高幅值的尖峰分布影响不大.同时降噪后κ场中高幅值尖峰分布的结果表明,降噪后不同模型间高幅值尖峰分布的差别还是非常明显的.对于尺度-尺度相关统计,分析了不同模型的尺度-尺度相关系数的累积概率分布函数,w=-1.2的模型与w=-0.8和w=-1.0的模型的差别能达到20%和30%.因此尺度-尺度相关的统计结合尖峰数目的统计,可以做为确定暗能量状态参数的一种新的手段.

In order to study the weak gravitational lensing effect in different cosmology models, the 2 dimensional k field samples are generated by using the ray-tracing method with high-resolution N-body simulation data. These samples correspond to three models, with different dark energy equations of state parameter, i.e., w = -0.8, w = -1.0 and w = -1.2, and with the field of view of 3° × 3°. It is assumed that all galaxies as the ambient sources are distributed in the plane of z = 1. The statistics of the peak counting and scale-scale correlation are performed and the results show that the peak distributions of the noisy s field among different models can be distinguished. The noise has changed the peak distributions of the medium and low levels, but has nearly no effect on high level peaks. After denoising the noise, the differences of high level peak distributions among the three models become even clearer. For the scale-scale correlation statistics, the cumulative probability distribution functions of the scale-scale coefficients are compared, and the deviations from the model of w = -1.2 for the models with w = -0.8 and w = -1.0 can reach 20% and 30%, respectively. When the two statistical methods are used together, the results can be taken as a new indicator of the dark energy equation of state parameter.