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arXiv 2008.11172astro-ph.GAhep-exhep-ph
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Milky Way的平衡轴对称晕模型及其对直接和间接DM搜索的意义

Equilibrium axisymmetric halo model for the Milky Way and its implications for direct and indirect DM searches

Mihael Petac

摘要:

我们第一次提供了自洽的轴对称相空间分布模型的银河系的暗物质(DM)晕,仔细匹配对最新的运动学测量,通过贝叶斯分析。通过使用广泛的先验的个别银河组件,我们得到保守的估计进入直接和间接DM搜索的解释的天体物理因素。虽然得到的DM密度分布与以前的研究,暗示$ρ_\odot \approx 10^{-2} \, M_\odot / \mathrm{pc}^3$,重子盘的存在导致显着差异的本地DM速度分布相比,标准的晕模型。对于直接检测,这意味着在检测器最大灵敏度附近的DM质量处的横截面极限大约强30%,并且在质量范围的下端处的极限弱一个数量级。此外,通过执行蒙特卡罗模拟为即将到来的DARWIN和DarkSide-20 k实验,我们证明,在成功检测到重DM与耦合低于当前的限制,精心构造的轴对称模型可以消除偏见,减少不确定性超过50%的重建DM耦合和质量,而且还有助于在一个更可靠的散射算子的测定。此外,由重子盘引起的速度各向异性可以导致显着更大的年度调制幅度和相当大的差异,在预期的DM诱导事件的方向分布。对于间接搜索,我们提供了差分$J$ -因子,并计算了几个时刻的相对速度分布,需要预测速度依赖的湮灭率。然而,我们发现准确的预测仍然受到银河系中心附近DM分布的巨大不确定性的阻碍。

英文摘要:

We for the first time provide self-consistent axisymmetric phase-space distribution models for the Milky Way's dark matter (DM) halo which are carefully matched against the latest kinematic measurements through Bayesian analysis. By using broad priors on the individual galactic components, we derive conservative estimates for the astrophysical factors entering the interpretation of direct and indirect DM searches. While the resulting DM density profiles are in good agreement with previous studies, implying $ρ_\odot \approx 10^{-2} \, M_\odot / \mathrm{pc}^3$, the presence of baryonic disc leads to significant differences in the local DM velocity distribution in comparison with the standard halo model. For direct detection, this implies roughly 30% stronger cross-section limits at DM masses near detectors maximum sensitivity and up to an order of magnitude weaker limits at the lower end of the mass range. Furthermore, by performing Monte-Carlo simulations for the upcoming DARWIN and DarkSide-20k experiments, we demonstrate that upon successful detection of heavy DM with coupling just below the current limits, the carefully constructed axisymmetric models can eliminate bias and reduce uncertainties by more then 50% in the reconstructed DM coupling and mass, but also help in a more reliable determination of the scattering operator. Furthermore, the velocity anisotropies induced by the baryonic disc can lead to significantly larger annual modulation amplitude and sizable differences in the directional distribution of the expected DM-induced events. For indirect searches, we provide the differential $J$-factors and compute several moments of the relative velocity distribution that are needed for predicting the rate of velocity-dependent annihilations. However, we find that accurate predictions are still hindered by large uncertainties regarding the DM distribution near the galactic center.

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