Constraining Cosmological Parameters with Galaxy Cluster Phase Spaces

1914年，爱因斯坦提出了广义相对论（GR）的基础，用空间和时间的几何来解释引力。爱因斯坦的广义相对论开启了宇宙起源和演化科学（“宇宙学”）的新科学范式转变的开端。这是一个黄金时代，类似于柏拉图、哥白尼和牛顿的时代，我们有幸见证了这种范式的实时转变。当数据和科学方法将理论推向极限时，所有的科学范式都会经历长时间的严格检验。宇宙是如此巨大，以至于存在适用于GR的物理尺度，但很难对其进行测试。以星系团为例，它们是宇宙中最大的受引力约束的物体。星系团在数千万光年的尺度上捕获星系。比我们的银河系大100倍)。爱因斯坦的广义相对论还适用于如此大的时空距离吗？星系团的逃逸速度是本地牛顿引力势和宇宙膨胀加速度的结合。星系团的弱透镜质量分布可以用来预测引力牛顿分量和宇宙学的逃逸速度分布。这种联合分析提供了一种新的直接途径来约束宇宙膨胀的动力学，并可以同时测试GR和我们的标准Lambda CDM宇宙学范式，时间演化暗能量，变色龙引力等等。我们将使用密歇根麦哲伦光纤系统（M2FS）收集100-200个星系团成员光谱，用于暗能量调查（DES）足迹内的星系团的逃逸速度。在似然分析中，我们将直接比较弱透镜预测的逃逸速度分布与从M2FS数据中观测到的分布。在哈勃常数的前提下，与超新星或CMB相比，该探测器可以在暗能量状态方程参数上达到类似或更好的精度。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In 1914, Einstein brought forth his foundations for GeneralRelativity (GR) to explain gravity using the geometry of space andtime. Einstein's GR ushered in the beginning of a new scientificparadigm shift for the science of the origin and evolution of theuniverse ("Cosmology"). This is now a golden age, similar to thecenturies around Plato, Copernicus and Newton, and we are privilegedto be witnesses to this paradigm shift in real-time. All scientificparadigms go through a long period of intense testing, as the data andthe scientific methods push the theory to its limits. The Universe isso vast that there are physical scales on which GR should apply, butwhich have been difficult to test. Consider clusters of galaxies,which are the largest gravitationally bound objects in the Universe.Clusters entrap galaxies on scales of tens of millions of light years(i.e, 100 times larger than our own Milky Way). Does Einstein's GRstill apply over such large distances in space-time?The escape velocity from a galaxy cluster is a combination of thelocal Newtonian gravitational potential and the acceleration of theexpansion of the Universe. Weak lensing mass profiles of clusters canbe used to predict the escape velocity profile from the gravitationalNewtonian component and cosmology. This joint analysis provides a newdirect avenue to constrain the dynamics of the expanding Universe andcan simultaneously test GR and our standard Lambda CDM cosmologicalparadigm, time evolving dark energy, Chameleon gravity, and more. Wewill use the Michigan Magellan Fiber System (M2FS) to collect 100-200galaxy cluster member spectra for escape velocities of clusters withinthe Dark Energy Survey (DES) footprint. We will directly compare theweak-lensing predicted escape velocity profiles to the observedprofiles from the M2FS data in a likelihood analysis. Given a Hubbleconstant prior, this probe can achieve similar or better precision onthe dark energy equation of state parameters compared to supernovae orthe CMB.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.