Title: Reconstructing the three-dimensional local dark matter velocity distribution Show Chinese title

Title: 重建三维局部暗物质速度分布

Abstract: Directionally sensitive dark matter (DM) direct detection experiments present the only way to observe the full three-dimensional velocity distribution of the Milky Way halo local to Earth. In this work we compare methods for extracting information about the local DM velocity distribution from a set of recoil directions and energies in a range of hypothetical directional and non-directional experiments. We compare a model independent empirical parameterisation of the velocity distribution based on an angular discretisation with a model dependent approach which assumes knowledge of the functional form of the distribution. The methods are tested under three distinct halo models which cover a range of possible phase space structures for the local velocity distribution: a smooth Maxwellian halo, a tidal stream and a debris flow. In each case we use simulated directional data to attempt to reconstruct the shape and parameters describing each model as well as the DM particle properties. We find that the empirical parametrisation is able to make accurate unbiased reconstructions of the DM mass and cross section as well as capture features in the underlying velocity distribution in certain directions without any assumptions about its true functional form. We also find that by extracting directionally averaged velocity parameters with this method one can discriminate between halo models with different classes of substructure. Show Chinese abstract

Abstract: 方向敏感的暗物质（DM）直接探测实验是唯一能够观测地球附近银河晕三维速度分布的方法。 在这项工作中，我们比较了从一系列假想的方向性和非方向性实验中的一组反冲方向和能量提取局地暗物质速度分布信息的方法。 我们对比了一种基于角度离散化的模型无关经验参数化方法与一种假设知道分布函数形式的模型相关方法。 这些方法在三种不同的晕模型下进行了测试，涵盖了局地速度分布可能相空间结构的范围：平滑的麦克斯韦晕、潮汐流以及碎片流。 在每种情况下，我们都使用模拟的方向性数据尝试重构描述每个模型及其暗物质粒子特性的形状和参数。 我们发现，经验参数化方法能够准确无偏地重建暗物质质量和截面，并且能够在某些方向上捕捉到潜在速度分布中的特征，而无需对其真实函数形式作出任何假设。 我们还发现，通过用这种方法提取方向平均速度参数，可以区分具有不同子结构类别的晕模型。