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: 定向敏感暗物质（DM）直接探测实验是观察地球附近银河系晕的完整三维速度分布的唯一途径。 在本工作中，我们比较了从一组假设的方向性和非方向性实验中的散射方向和能量中提取本地DM速度分布信息的方法。 我们比较了一种基于角度离散化的模型无关的经验参数化方法与一种模型依赖的方法，后者假设已知分布的函数形式。 这些方法在三种不同的晕模型下进行了测试，这些模型涵盖了本地速度分布可能的相空间结构范围：一个平滑的麦克斯韦晕、一个潮汐流和一个碎片流。 在每种情况下，我们使用模拟的方向数据尝试重建描述每个模型的形状和参数以及DM粒子性质。 我们发现，经验参数化方法能够准确无偏地重建DM质量与截面，并在某些方向上捕捉到潜在速度分布的特征，而无需对其真实函数形式做出任何假设。 我们还发现，通过使用这种方法提取方向平均的速度参数，可以区分具有不同子结构类别的晕模型。