宇宙微波背景辐射的大尺度反常研究

The measurements of temperature distribution of the cosmic microwave background (CMB) has reached an unprecedented precision since the launch of the Planck Satellite. The precise data that has being collected throughout the years were not able to shed light in some unexpected features reported for the first time in the Cosmic Microwave Explorer (COBE) data. Anomalies regarding the temperature fluctuations in the CMB sky, considering that the universe obeys the physics described by the LCDM model, has been the focus of a great debate. Among them, the quadrant asymmetry reported in the WMAP data and confirmed in the Planck data needs to be better characterized. First, it is important to understand if this observed power asymmetry is related to secondary effects, such as aberration and Doppler, related to our motion in respect to the rest frame of the CMB or if it has a cosmological origin. In either way, the result will bring important contributions to the CMB studies: New ways to treat the data in order to avoid misleading interpretation of the physics behind the phenomena or the need of building a new cosmological model able to explain the observed features in the CMB temperature distribution. Different observables may be of fundamental importance in revealing the mystery around the CMB temperature anomalies. The CMB polarization is among the targets of the next cosmological experiments. Isotropy violations in the polarization field could point to a new physics, being this information valuable to constraint new models of the universe.

Planck卫星的观测使得对宇宙微波背景辐射（CMB）中温度各向异性的测量达到了前所未有的精度，并发现或证实了一系列超出标准模型的反常现象，包括象限不对称反常。这些发现有可能导致LCDM模型面临挑战。本项目中，我们将深入讨论这些反常，特别是象限不对称现象。首先，我们将研究该功率不对称是否由其他二阶效应导致的，如太阳系运动的多普勒效应和偏折效应，或与偶极调制相关，抑或是由某种宇宙学原因导致的。若是前者，则需要在未来的数据分析中将其扣除，以免误导CMB数据的宇宙学解释；若是后者，则该反常预示着早期宇宙中的新物理。因此无论何种情况，都需要对这些反常现象进行认真研究。另一方面，我们还将研究推广到大尺度的CMB极化数据中（预计Planck近期会释放相关数据），利用各种非高斯统计检验来研究其可能的大尺度反常。通过对极化的研究，将有利于揭示CMB反常可能的物理起源，以及更好地限制新物理。

在本项目中，我们针对宇宙微波背景辐射及其相关的宇宙学参数测量开展研究。 在研究中，我们发展了闵可夫斯基泛函的方法来检验宇宙微波背景辐射B-模天图的统计特性，并发现该方法可以探测到B-模天图中微小的E-B泄露信号；我们研究了利用微波背景辐射数据，结合其他宇宙学观测数据来限制相互作用暗能量模型；我们研究了宇宙微波背景辐射的偏好方向等大尺度反常的统计特性；研究了利用引力波标准汽笛来校准超新星等相关问题；我们将模型无关的ABS前景分离方法应用到微波背景的极化数据中，并利用数值模拟显示了方法的可靠性。在这些方面，我们共发表了8篇论文，其中第一作者3篇。另外还有一篇第一作者论文已经投稿。完成了该项目的设定目标。