Towards Robust Measurements of H0 with Dark Standard Candles

使用深色标准烛光对 H0 进行稳健测量

• 批准号: 2307026
• 负责人: Dragan Huterer
• 金额: $ 64.74万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307026&HistoricalAwards=false
• 关键词: Towards; Robust; Measurements; H0; Dark

Measurements of the expansion rate of the universe -- the Hubble constant -- have historically been uncertain, but have in the past two decades converged to the concordance value. However, a major recent development in cosmology has been the disagreement between the Hubble constant determinations by two major cosmological probes. Namely, the precision (indirect) measurement of the Hubble constant by the cosmic microwave background anisotropies gives a much lower value for the expansion rate than the direct determination from nearby galaxies and type Ia supernovae. The two measurements are mutually inconsistent at the "five sigma" level, corresponding to confidence of about 99.9999%. Search for the explanation of this so-called Hubble tension has become a central effort in cosmology. Scientists at the University of Michigan and the University of Pennsylvania propose to dramatically improve the reliability of an alternative method to measure the Hubble constant, which has the power to shed new light or outright resolve the Hubble tension. This method utilizes the so-called ``dark standard siren'' gravitational-wave events. As part of this project, the team will also engage in a number of outreach activities, including running an annual summer course for high-school students and organizing the biannual Cosmology Summer School (at Michigan); as well as organizing lectures during AstroFest and running the Neighborhood Workshop on Astrophysics and Cosmology (at Penn State).Standard sirens are mergers that result in observed gravitational-wave signatures whose wave-forms provide distances to these events. The dark sirens are those events in which the electromagnetic counterpart is not discovered (and the corresponding redshift not measured), complicating the consequent determination of the Hubble constant. The team will study how the cross-correlation between galaxies and gravitational-wave dark sirens can be used to measure the Hubble constant. This cross-correlation approach should allow a much cleaner separation of the cosmological signal from biases that are due to a variety of systematic errors, but can also be purely statistical. The team will thoroughly test this method against the systematic errors, then apply it to current data, and identify prospects for Hubble-constant constraints with future data. Finally, the team will also investigate the effect of astrophysical systematics on the ability to recover the Hubble constant.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.

宇宙膨胀率的测量 - 哈勃常数 - 历史上一直不确定，但在过去的二十年中，它融合到了一致价值。然而，宇宙学的最新发展是两个主要的宇宙学探针的哈勃恒定确定之间的分歧。也就是说，宇宙微波背景各向异性对哈勃常数的精度（间接）测量比从附近的星系和IA型超新星的直接确定的膨胀率值要低得多。这两个测量值在“五个Sigma”水平上相互不一致，对应于约99.999％的置信度。寻找这种所谓的哈勃张力的解释已成为宇宙学的核心努力。密歇根大学和宾夕法尼亚大学的科学家建议大幅提高替代方法的可靠性，以衡量哈勃常数，这有能力摆脱新的光线或直接解决哈勃张力。这种方法利用所谓的``暗标记''重力波事件。作为该项目的一部分，该团队还将从事许多外展活动，包括为高中生举办年度夏季课程以及组织双年度宇宙学暑期学校（在密歇根州）；除了在Astrofest期间组织讲座并在宾夕法尼亚州（Penn State）举办有关天体物理学和宇宙学的邻里研讨会。标准警报器是合并，导致观察到的重力波签名，其波形形成的波形为这些事件提供了距离。黑暗的警笛是那些未发现电磁对应物（未测量的红移）的事件，从而使随之而来的哈勃常数得出复杂化。该团队将研究星系与重力波暗警报器之间的互相关如何测量哈勃常数。这种互相关方法应允许将宇宙学信号与由于多种系统误差引起的偏见进行更清洁的分离，但也可以纯粹是统计。团队将针对系统错误彻底测试此方法，然后将其应用于当前数据，并确定使用未来数据的哈勃构成约束的前景。最后，团队还将研究天体物理系统学对恢复哈勃常数能力的影响。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响评估标准来通过评估来获得支持的。