论文标题
在z $ \ sim0.3 $的银河秤中探测一般相对论
Probing General Relativity in galactic scales at z $\sim0.3$
论文作者
论文摘要
一般相对性（GR）已成功测试，主要是在太阳系量表上进行的。但是，在过去的几十年中，星系尺度的测试变得流行。在这项工作中，我们研究了$η_\ text {ppn} $参数，该参数通常由宇宙学线性扰动度量中出现的两个标量势的比率定义。在GR和消失的各向异性应力张量的假设下，$η_\ text {ppn} = 1 $。使用ALMA，HST和VLT/MUSE DATA，我们使用重力镜头和银河动力学结合质量测量，用于SDP.81镜头银河系（$ z = 0.299 $），以限制$η_\ text {ppn} $。通过使用柔性且自洽的质量概况，我们的基金模型考虑了恒星质量和暗物质光环的贡献，以重建镜头的星系和空间分辨的恒星运动学。在考虑了与大众模型，宇宙学和运动学有关的系统不确定性之后，$η_{\ text {ppn}} = 1.13^{+0.03} _ { - 0.03} _ { - 0.03} \ pm0.20 \ pm0.20 \，（\ pm0.20 \，（\ sys}）需要更好的光谱数据来将系统学降低并将不确定性提高到百分比水平，因为我们的分析表明，系统的主要来源与运动学有关，这在很大程度上取决于光谱的信噪比。
General Relativity (GR) has been successfully tested mainly at Solar system scales; however, galaxy-scale tests have become popular in the last few decades. In this work, we investigate the $η_\text{PPN}$ parameter, which is commonly defined by the ratio of two scalar potentials that appears in the cosmological linearly perturbed metric. Under the assumption of GR and a vanish anisotropic stress tensor, $η_\text{PPN}= 1$. Using ALMA, HST, and VLT/MUSE data, we combine mass measurements, using gravitational lensing and galactic dynamics, for the SDP.81 lens galaxy ($z = 0.299$) to constrain $η_\text{PPN}$. By using a flexible and self-consistent mass profile, our fiducial model takes into account the contribution of the stellar mass and a dark matter halo to reconstruct the lensed galaxy and the spatially-resolved stellar kinematics. We infer, after accounting for systematic uncertainties related to the mass model, cosmology and kinematics, $η_{\text{PPN}} = 1.13^{+0.03}_{-0.03}\pm0.20\,(\text{sys})$, which is in accordance with GR predictions. Better spectroscopy data are needed to push the systematics down and bring the uncertainty to the percentage level since our analysis shows that the main source of the systematics is related to kinematics, which heavily depends on the signal-to-noise ratio of the spectra.
