A unified approach to the study of dark matter and baryons in the large scale structure of the Universe

对宇宙的研究偶然发现了两个谜团：宇宙是由5%的正常物质组成的，20%的未知物质，暗物质，75%的令人费解的能量形式，暗能量。一项全球范围的探索正在进行，以探测、绘制和解释这些黑暗成分。在过去的十年里，十几个国际团队组织了大型调查，其中包括最大的地面望远镜和最先进的卫星，并开发了突破性的计算技术来分析数千tb的数据。引力透镜是揭示暗物质存在的首选工具。根据爱因斯坦的广义相对论，来自遥远星系的光会被存在于光源和观察者之间的巨大天体扭曲。此属性可用于衡量和映射任何其他方法无法检测到的物质。15年前，L. Van Waerbeke是为这一新的研究领域奠定理论和观察基础的先驱之一。通过统计分析数百万个背景星系的扭曲形状，他首次发现了大规模结构的引力透镜效应。今天，引力透镜在几个国际卫星项目中处于领先地位，比如美国的宽视场红外巡天望远镜和欧洲的欧几里得望远镜。在过去的五年里，L. Van Waerbeke领导了一个名为CFHTLenS的国际团队，他们将引力透镜的精度和可靠性提升到了一个新的水平。CFHTLenS分析了4tb的数据，提供了第一张大尺度的暗物质地图，这反过来又为星系如何形成以及暗物质如何在其光晕中演化提供了线索。仅2013年，CFHTLens的论文被引用超过190次。该团队在加拿大天文数据中心公开了他们高度处理的数据，并在头12个月内获得了20万次点击。在过去的二十年里，大爆炸理论得到了大量证据的证实，比如对宇宙微波背景辐射（CMB）的著名观测，但一些差距仍然存在。在宇宙历史的35亿年里，50%的质子和电子对天文学家来说是不可见的；在过去的15年里，x射线和微波卫星一直在搜寻这些“失踪的重子”。2013年，L. Van Waerbeke表明，引力透镜与CMB观测相结合可以探测到缺失的重子的存在，从而打开了一个新的研究领域的大门，可以测量它们的温度和密度，探索它们如何在恒星中循环，并为大爆炸理论带来新的证实，并为结构形成提供新的线索。引力透镜数据也可以与其他大型调查进行交叉相关（GLx），以探测重子的物理特性。在未来的五年里，L Van Waerbeke将培养一个由两名博士后、四名研究生和至少五名本科生组成的团队，开发新的计算工具和模拟，以成为GLx的领先团队。两种已知的物质，重子和暗物质，是交织在一起的，L. Van Waerbeke认为是时候建立将它们结合在一起的模型了。在接下来的十年里，将进行更大规模的调查，覆盖整个天空。所有可能状态下的暗物质和重子都将被绘制出来。L. Van Waerbeke希望为有效分析这些大量涌入的数据奠定理论和实践基础。在他的团队中受过培训的人员将向全世界输出这种专业知识。在不久的将来，他预计这一研究领域会有深远的应用，比如测量难以捉摸的中微子粒子的质量，完善爱因斯坦的引力理论。

The study of the universe is stumbling upon two mysteries : it is made for 5% of normal matter, 20% of an unknown type of matter, dark matter, and for 75% of a puzzling form of energy, dark energy. A worldwide quest is underway to probe, map and explain those dark components. In the past ten years, a dozen of international teams organized mega surveys involving the largest ground based telescopes and state of the art satellites, and developed ground breaking computing techniques to analyse thousands of terabytes of data.Gravitational lensing is the tool of choice to reveal the presence of dark matter. According the Einstein's general theory of relativity, light from distant galaxies is distorted by massive astronomical bodies present between the source and the observer. This property can be used to weigh and map matter that cannot be detected by any other means. Fifteen years ago, L. Van Waerbeke was among the pioneers who laid the theoretical and observational foundations of this new field of research. By statistically analyzing the distorted shapes of millions of background galaxies, he performed the first detection of gravitational lensing by a large scale structure. Today, gravitational lensing is leading the science in several international satellite projects like Wide Field Infrared Survey Telescope in the US and Euclid in Europe. For the past five years, L. Van Waerbeke has led an international team, CFHTLenS, who brought gravitational lensing to a new level of precision and reliability. Analyzing 4 TB of data, CFHTLenS provided the first large scale map of dark matter, which in turn provides clues about how galaxies formed and how dark matter evolved in their halos. In 2013 alone, CFHTLens papers received more than 190 citations. The team made their highly processed data publicly available at the Canada Astronomy Data Centre and received 200,000 hits in the first twelve months.For the past twenty years, the Big Bang theory has been confirmed by a large body of evidence, like the famous observations of the cosmic microwave background radiation (CMB), but some gaps persist. Three and a half billion years into the history of the universe, 50% of protons and electrons became invisible to astronomers; for the past fifteen years, these “missing baryons” have been searched by X-ray and microwave satellites. In 2013, L. Van Waerbeke showed that gravitational lensing combined with CMB observations can detect the presence of missing baryons, opening the door to a new field of research that could measure their temperature and density, explore how they are recycled in stars, and bring a new confirmation of the Big Bang theory, and shed a new light on structure formation. Gravitational lensing data could also be cross correlated (GLx) with other mega surveys to probe the physics of baryons.In the five coming years, L Van Waerbeke will train a team of two postdoctoral fellows and four graduate students, and at least five undergraduate students, to develop new computing tools and simulations in order to become the leading team in GLx. The two known types of matter, baryons and dark matter, are intertwined, and L. Van Waerbeke believe that it is time to build models combining them together. In the coming decade, ever larger surveys will be undertaken, covering the entire sky. Dark matter and baryons in all possible stated will be mapped. L. Van Waerbeke wants to lay the theoretical and practical foundations to efficiently analyze this massive influx of data. Personnel trained in his team will export this expertise worldwide. In the near future, he expects this field of research to have far reaching applications, like measuring the mass of the elusive neutrino particles and refining Einstein's theory of gravity.