Astrometric mock observations for determining the local dark matter density
Astrometric mock observations for determining the local dark matter density
复制标题
DOI：
10.1051/0004-6361/201321355
复制
发表时间：
2013-02
影响因子：
6.5
通讯作者：
Shigeki Inoue;N. Gouda
中科院分区：
文献类型：
--
作者：
Shigeki Inoue;N. Gouda
语境。确定太阳系局部暗物质密度是天文学中的一个经典问题。最近，设计了一种根据恒星分布和垂直于银河平面的垂直速度色散剖面确定局部暗物质密度的新方法。该方法的优点是废除了传统的近似方法并且仅使用很少的假设。目标。我们的目标是仔细审查这种方法并检查天体测量观测的不确定性的影响。我们讨论了局部暗物质密度的确定如何随视差、自行和视线速度测量的观测精度而变化。方法。为了检查观测不精确性的影响，我们为基于分析星系模型的动态示踪剂恒星创建了模拟观测数据，并将参数化观测误差应用于模拟数据。我们通过将该方法应用于模拟数据来评估确定暗物质密度的准确性。此外，我们还估计了准确确定暗物质密度所需的样本量和观测精度。结果。我们发现，如果样本量和观测精度令人满意，该方法能够准确确定局部暗物质密度。所需的样本量约为 6000 颗星。视差和自行的随机误差可能导致对暗物质密度的系统性高估。我们估计在距太阳 1 kpc 处视差测量所需的精度约为 0.1−0.3 毫弧秒；自行精度似乎并不像视差那么重要。此外，我们发现视线速度误差可能导致暗物质密度的低估或高估，这取决于误差的距离依赖性。结论。从这些结果来看，我们预计，如果应用这种方法，使用依巴谷星表会高估局部暗物质密度，因为视差测量不精确；然而，我们强调该方法的能力。我们预计盖亚将提供足够精确的数据来确定局部暗物质密度。
Context. To determine thelocal dark matter density of the solar system isaclassical problem inastronomy. Recently, a novel method of determining the local dark matter density from stellardistribution and verticalvelocity dispersion profiles perpendicular tothe Galactic plane was devised. This method has the advantage of abolishing conventional approximations and using only a few assumptions. Aims. Our aims are to carefully scrutinize this method and to examine influences by uncertainties of astrometric observations. We discuss how the determinations of the local dark matter density vary with observational precisions on parallax, proper motion, and line-of-sight velocity measurements. Methods. To examine the influences by the observational imprecision, we created mock observation data for stars that are dynamical tracers based on an analytical galaxy model and applied parametrized observational errors to the mock data. We evaluated the accuracy of determining the dark matter density by applying the method to the mock data. In addition, we estimated a sample size and observational precision required to determine the dark matter density with accuracy. Results. We find that the method is capable of determining the local dark matter density with accuracy if the sample size and observational precisions are satisfactory. The required sample size is approximately 6000 stars. The random errors of parallaxes and proper motions can cause systematic overestimation of the dark matter density. We estimate the required precisions of the parallax measurements to be approximately 0.1−0.3 milliarcsec at 1 kpc away from the Sun; the proper motion precisions do not seem to be as important as the parallaxes. Moreover, we find that the line-of-sight velocity errors can cause either underestimation or overestimation of the dark matter density, which is contingent on distance-dependence of the errors. Conclusions. From these results, we expect that using the Hipparcos catalog would overestimate the local dark matter density because of the imprecise parallax measurements if this method is applied; however, we emphasize the capability of the method. We expect that Gaia will provide data precise enough to determine the local dark matter density.