Toward a Direct Measure of the Galactic Acceleration
Toward a Direct Measure of the Galactic Acceleration
复制标题
DOI：
10.3847/2041-8213/abb9b5
复制
发表时间：
2020-07
期刊：
影响因子：
--
通讯作者：
S. Chakrabarti;J. Wright;P. Chang;A. Quillen;P. Craig;Joey Territo;E. D’Onghia;K. Johnston
中科院分区：
文献类型：
--
作者：
S. Chakrabarti;J. Wright;P. Chang;A. Quillen;P. Craig;Joey Territo;E. D’Onghia;K. Johnston
高精度光谱仪不仅可以发现系外行星，还可以提供银河系动力学的基本测量。在大约10年的基线上，银河系引力场对银河系中平面上方千秒差距尺度的恒星的视线速度的预期变化是几十cm s−1，并且可能被当前一代的高精度摄谱仪检测到。在这里，我们提供了理论上的期望，这种测量的基础上的静态模型的银河系和孤立的银河系的模拟，以及从控制动态模拟的银河系与矮星系的相互作用。我们模拟了一个人口合成模型，分析了行星和双星对银河系加速度信号的贡献。我们发现，虽然低质量，长周期的行星同伴是银河系加速度信号的污染物，他们的贡献是非常小的。我们对Lick-Carnegie系外行星巡天HIRES/Keck精密径向速度（RV）巡天2010年数据的分析表明，标准RV恒星的RV曲线的斜率与太阳附近局部银河系加速度的预期一致，误差范围内，斜率的误差与观测次数的平方根成反比。因此，我们证明，调查低内在恒星抖动在千秒差距以上的银河系中平面的实际样本大小的距离，可以使暗物质密度的直接测定。
High-precision spectrographs can enable not only the discovery of exoplanets, but can also provide a fundamental measurement in Galactic dynamics. Over about 10 year baselines, the expected change in the line-of-sight velocity due to the Galaxy’s gravitational field for stars at ∼kiloparsec scale distances above the Galactic midplane is ∼few tens of cm s−1, and may be detectable by the current generation of high-precision spectrographs. Here, we provide theoretical expectations for this measurement based on both static models of the Milky Way and isolated Milky Way simulations, as well from controlled dynamical simulations of the Milky Way interacting with dwarf galaxies. We simulate a population synthesis model to analyze the contribution of planets and binaries to the Galactic acceleration signal. We find that while low-mass, long-period planetary companions are a contaminant to the Galactic acceleration signal, their contribution is very small. Our analysis of ∼10 years of data from the Lick–Carnegie Exoplanet Survey HIRES/Keck precision radial-velocity (RV) survey shows that slopes of the RV curves of standard RV stars agree with expectations of the local Galactic acceleration near the Sun within the errors, and that the error in the slope scales inversely as the square root of the number of observations. Thus, we demonstrate that a survey of stars with low intrinsic stellar jitter at kiloparsec distances above the Galactic midplane for realistic sample sizes can enable a direct determination of the dark matter density.