Collaborative Research: Imaging the Beginning of Time from the South Pole: The next Stage of the BICEP Program

“大爆炸”理论提供了一个完善的宇宙学模型，从宇宙最早的已知时期到随后的大规模演化。该模型追溯了宇宙的膨胀，从一个非常高的密度和温度状态的初始条件开始，这几乎是但不是完全光滑的，它提供了一个广泛的现在已知的现象，包括丰富的轻元素，宇宙微波背景辐射，和大尺度结构的分布的全面解释。虽然已建立的“大爆炸”理论留下了解释初始条件的问题，但目前的证据与整个可观测宇宙是在一个戏剧性的，指数级的“膨胀”中产生的，持续了大约一万亿分之一秒的万亿分之一。在这个短暂的暴胀时期之后，宇宙继续膨胀，但速度较慢。虽然基本的“暴胀范式”被大多数科学家所接受，但导致暴胀的详细粒子物理机制仍然未知。人们相信，这种剧烈的时空膨胀会产生现在正在膨胀的宇宙中传播的原初引力波，从而形成宇宙引力波背景（CGB），其振幅测量了暴胀的能量尺度。CGB在宇宙微波背景（CMB）的偏振中留下了一个微弱的签名，检测这种偏振签名可以说是当今宇宙学中最重要的目标。 这个奖项将解决人类提出的最古老的问题之一，“宇宙是如何开始的？“，它是通过在地球上最有趣的地方之一，南极洲的南极站进行的观测来实现的。由社区推动的Astro 2010年十年期调查将寻找CGB描述为“最令人兴奋的探索”，强调“需要对旨在探测CMB（B模式）极化的系统进行中期投资”。2005年，NASA/DOE/NSF CMB研究工作组将这一主题确定为该领域的最高优先级，并确定了引力波与密度波动之比的目标灵敏度为r ~ 0.01。这样的测量保证了对慢卷暴胀模型的最终测试，该模型通常预测引力波信号在r~0.01或更高，产生CMB B模式波动，在角度尺度上达到峰值。正在进行的BICEP系列实验致力于这一科学目标。该实验于2006年开始在南极运行，一直在无情地绘制一个800平方度的天空区域，该区域位于银河系前景较低的区域，称为南洞。该奖项将支持CMB“第三阶段”科学的科学观测和分析，BICEP阵列计划将在五个频带测量偏振天空。它预计将达到最终的灵敏度膨胀引力波的振幅“西格玛r”0.005，外推从实现的性能和保守的会计后，银河尘埃，银河同步辐射，和CMB透镜前景。这一测量将为大多数缓慢的通货膨胀模型提供一个明确的测试，并将实现或超过工作队在2005年为灵敏度设定的目标。该项目将继续在这方面成绩斐然的实验室为本科生、研究生和博士后研究员（包括来自代表人数不足群体的研究员）提供出色的培训。南极洲的宇宙学和研究都抓住了公众的想象力，使这种结合成为激发科学兴趣的非常有效的工具。

The theory of the "Big Bang" provides a well-established cosmological model for the Universe from its earliest known periods through its subsequent large-scale evolution. The model traces the expansion of the Universe, starting from initial conditions of a very high density and temperature state which is almost but not perfectly smooth, and it offers a comprehensive explanation for a broad range of now-known phenomena, including the abundance of light elements, the cosmic microwave background radiation, and the distribution of large scale structures. While the established "Big Bang" theory leaves open the question of explaining the initial conditions, current evidence is consistent with the entire observable Universe being spawned in a dramatic, exponential "inflation" of a sub-nuclear volume that lasted about one trillionth of a trillionth of a trillionth of a second. Following this short inflationary period, the Universe continues to expand, but at a less rapid rate. While the basic "inflationary paradigm" is accepted by most scientists, the detailed particle physics mechanism responsible for inflation is still not known. It is believed that this violent space-time expansion would have produced primordial gravitational waves now propagating through the expanding universe, thus forming a cosmic gravitational-wave background (CGB) the amplitude of which measures the energy scale of inflation. The CGB imprints a faint signature in the polarization of the Cosmic Microwave Background (CMB), and detecting this polarization signature is arguably the most important goal in cosmology today. This award will address one of the oldest questions ever posed by mankind, "How did the Universe begin?", and it does so via observations made at one of the most intriguing places on Earth, South Pole Station in Antarctica. The community-driven Astro2010 Decadal Survey described the search for the CGB as "the most exciting quest of all", emphasizing that "mid-term investment is needed for systems aimed at detecting the (B-mode) polarization of the CMB". In 2005, the NASA/DOE/NSF Task Force on CMB Research identified this topic as the highest priority for the field and established a target sensitivity for the ratio of gravitational waves to density fluctuations of r ~ 0.01. Such measurements promise a definitive test of slow-roll models of inflation, which generally predict a gravitational-wave signal around r~0.01 or above, producing CMB B-modes fluctuations that peak on degree angular scales. The ongoing BICEP series of experiments is dedicated to this science goal. The experiment began operating at South Pole in 2006 and has been relentlessly mapping an 800 square degree region of the sky in a region of low in Galactic foregrounds known as the Southern Hole. This award will support science observations and analysis for the CMB "Stage 3" science with the BICEP Array program that will measure the polarized sky in five frequency bands. It is projected to reach an ultimate sensitivity to the amplitude of inflationary gravitational waves of "sigma r" 0.005, extrapolating from achieved performance and after conservatively accounting for the Galactic dust, Galactic synchrotron radiation, and CMB lensing foregrounds. This measurement will offer a definitive test of most slow-roll models of Inflation, and will realize or exceed the goals set by the Task Force in 2005 for sensitivity. The project will continue to provide excellent training for undergraduate and graduate students and postdoctoral fellows (including those from underrepresented groups) in laboratories that have exceptional track records in this regard. Cosmology and research in Antarctica both capture the public imagination, making this combination a remarkably effective vehicle for stimulating interest in science.