arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.15097astro-ph.GA
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直接测量银河系的加速度

Towards a direct measure of the Galactic acceleration

Sukanya Chakrabarti, Jason Wright, Philip Chang, Alice Quillen, Peter Craig, Joey Territo, Elena D'Onghia, Kathryn V. Johnston, Robert J. De Rosa, Daniel Huber,… 展开作者

Sukanya Chakrabarti, Jason Wright, Philip Chang, Alice Quillen, Peter Craig, Joey Territo, Elena D'Onghia, Kathryn V. Johnston, Robert J. De Rosa, Daniel Huber, Katherine L. Rhode, Eric Nielsen

摘要:

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,对于银河系中平面上方$\sim$ kpc尺度距离的恒星,由于银河系引力场的影响,视线速度的预期变化为$\sim$几- 10 cm/s,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LCES HIRES/Keck精密视向速度(RV)巡天的$\sim$ 10年数据的分析表明,标准RV星的RV曲线的斜率在误差范围内与太阳附近的局部银河系加速度的预期一致,斜率误差与观测次数的平方根成反比。因此,我们表明,调查的恒星与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可以直接确定的暗物质密度。

英文摘要:

High precision spectrographs can enable not only the discovery of exoplanets, but can also provide a fundamental measurement in Galactic dynamics. Over about ten year baselines, the expected change in the line-of-sight velocity due to the Galaxy's gravitational field for stars at $\sim$ kpc scale distances above the Galactic mid-plane is $\sim$ few - 10 cm/s, 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 $\sim$ ten years of data from the LCES 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 kpc distances above the Galactic mid-plane for realistic sample sizes can enable a direct determination of the dark matter density.

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