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首页> 外文期刊>The Astrophysical Journal. Letters >Constraints on the shape of the milky way dark matter halo from jeans equations applied to sloan digital sky survey data
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Constraints on the shape of the milky way dark matter halo from jeans equations applied to sloan digital sky survey data

机译：适用于斯隆数字天空调查数据的牛仔裤方程式对银河系暗物质光晕形状的限制

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摘要

We search for evidence of dark matter in the Milky Way by utilizing the stellar number density distribution and kinematics measured by the Sloan Digital Sky Survey (SDSS) to heliocentric distances exceeding 10kpc. We employ the cylindrically symmetric form of Jeans equations and focus on the morphology of the resulting acceleration maps, rather than the normalization of the total mass as done in previous, mostly local, studies. Jeans equations are first applied to a mock catalog based on a cosmologically derived N-body+SPH simulation, and the known acceleration (gradient of gravitational potential) is successfully recovered. The same simulation is also used to quantify the impact of dark matter on the total acceleration. We use Galfast, a code designed to quantitatively reproduce SDSS measurements and selection effects, to generate a synthetic stellar catalog. We apply Jeans equations to this catalog and produce two-dimensional maps of stellar acceleration. These maps reveal that in a Newtonian framework, the implied gravitational potential cannot be explained by visible matter alone. The acceleration experienced by stars at galactocentric distances of 20kpc is three times larger than what can be explained by purely visible matter. The application of an analytic method for estimating the dark matter halo axis ratio to SDSS data implies an oblate halo with q DM = 0.47 ± 0.14 within the same distance range. These techniques can be used to map the dark matter halo to much larger distances from the Galactic center using upcoming deep optical surveys, such as LSST.
机译：我们利用恒星数密度分布和由斯隆数字天空调查（SDSS）测量的日心距超过10kpc的运动学，寻找银河系中暗物质的证据。我们采用Jeans方程的圆柱对称形式，并着重于所得加速度图的形态，而不是像以前（主要是本地研究）所做的那样对总质量进行归一化。 Jeans方程首先基于宇宙学派生的N-body + SPH模拟应用于模拟目录，并且成功恢复了已知的加速度（重力势梯度）。相同的模拟也用于量化暗物质对总加速度的影响。我们使用Galfast（旨在定量复制SDSS测量值和选择效果的代码）生成合成的星表。我们将Jeans方程应用于此目录，并生成恒星加速度的二维映射。这些图表明，在牛顿框架中，隐含的引力不能仅由可见物质来解释。恒星在20kpc的恒心距离上经历的加速度是纯可见物质所能解释的加速度的三倍。估计暗物质晕轴比对SDSS数据的分析方法的应用意味着在相同距离范围内q DM = 0.47±0.14的扁圆晕。这些技术可用于使用即将到来的深层光学勘测（例如LSST）将暗物质晕圈映射到距银河系中心更大的距离。

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