Collaborative Research: Using the Lyman Alpha Forest to Probe the Structure of the Universe

合作研究：利用莱曼阿尔法森林探测宇宙结构

• 批准号: 0098731
• 负责人: David Tytler
• 金额: $ 27万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0098731&HistoricalAwards=false
• 关键词: Collaborative; Research; Using; Lyman; Alpha

AST 0098731Tytler In the last few years, astronomers have shown that supernovae (SN), in distant galaxies are fainter than expected. The obvious explanation is that they are farther away than we had thought. If true, this implies that the expansion of the universe is speeding up. This change in expansion is attributed to a so called "vacuum energy" by theoretical physics. This discovery presents both major new opportunities, and a long list of troubling basic new questions. Up to now Gravity has been the hardest part of physics to understand, in part because it has been described by a single number: the Newtonian gravitational constant G which measures its strength. If the universe is speeding up there must be a second number, which should help us understand gravitational physics. In this way, astronomical observations are redefining our understanding of fundamental physics and the universe as a whole. The goals of this project are to provide an independent check of the claim that 70% of the energy density of the universe is some form of mysterious vacuum energy. Astronomical observations are the only way to explore the vacuum energy experimentally, because the effects are significant only over exceedingly large distances. In particular, this project will provide an independent check of the results from supernovae by using angular size as a distance measure. The amount of clumping of the gas between the galaxies will be measured both along the line of sight, and in angle across the sky. The relationship between the two measures gives the distance and hence the acceleration of the universe. The method is insensitive to changes in the state of the universe over long times. The project is urgent, because the vacuum energy remains an unconfirmed, though very plausible, result, and highly significant, because we will have the sensitivity to decisively rule out the amount of vacuum energy suggested by the supernovae, if none were present. In addition to providing an independent check on the SN decelerating universe measurement, this project will also give improved measurements of the clumping of gas between galaxies at early times. This clumping is believed to have arisen from primordial quantum fluctuations when the universe was young.. These fluctuations have been measured at different epochs, and in different ways. However, the methods used in the present project will give the only measurement of the amount of clumping of matter on galaxy sized scales at early times. These new data and simulations will be compared with theoretical predictions, to act as a check on recent investigations which suggest that our present ideas about the growth of small scale structure in the universe are inadequate. Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC).***

在过去的几年中，天文学家AST 0098731Tytler表明，遥远星系中的超新星（SN）比预期的薄弱。显而易见的解释是，它们比我们想象的要远。如果是真的，这意味着宇宙的扩展正在加速。这种扩展的变化归因于理论物理学所谓的“真空能”。这一发现既提出了主要的新机会，又提出了许多令人困扰的新问题。到目前为止，重力一直是物理学中最难理解的部分，部分原因是它已经用一个数字描述：牛顿重力常数g，它可以测量其强度。如果宇宙正在加速，必须有第二个数字，这应该有助于我们了解重力物理学。通过这种方式，天文观察重新定义了我们对基本物理和整个宇宙的理解。该项目的目标是独立检查宇宙能量密度的70％是神秘真空能量的某种形式的说法。天文观测是实验探索真空能量的唯一途径，因为这种效果仅在极大的距离内才是显着的。 特别是，该项目将通过使用角度大小作为距离度量来独立检查超新星的结果。星系之间的气体的结块量将沿着视线和横跨天空的角度测量。这两种措施之间的关系赋予了宇宙的距离，从而加速了宇宙的加速度。该方法对长时间的宇宙状态不敏感。该项目是紧迫的，因为真空能量仍然是未经证实的，尽管非常合理，但结果且非常重要，因为我们将具有果断地排除超新星建议的真空能量的敏感性，如果不存在。除了对SN减速的宇宙测量值提供独立检查外，该项目还将改进对早期星系之间气体团结的测量。据信，这种结块是由于宇宙年轻的原始量子波动而产生的。这些波动已在不同的时期和不同的方式测量。 但是，本项目中使用的方法将在早期的星系大小尺度上唯一的测量物质量。这些新的数据和仿真将与理论预测进行比较，以便对最近的研究进行检查，这表明我们目前关于宇宙中小规模结构增长的想法不足。该项目的资金由NSF外乳术天文学和宇宙学计划（AST/EXC）提供。***