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arXiv 2307.09501astro-ph.CO
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用宇宙计时器解决哈勃常数危机

Addressing the Hubble tension with cosmic chronometers

Michele Moresco

AI总结:

本文介绍宇宙计时器方法,通过测量年龄-红移关系斜率提供模型无关的膨胀历史,以独立证据应对哈勃常数危机,并展望未来测量与预测。

摘要:

在发现宇宙加速膨胀二十年后,一项新发现正在挑战我们对宇宙的理解。最近的研究表明,哈勃常数(即今天测得的膨胀速度)在从原始宇宙的宇宙微波背景辐射或本地宇宙的造父变星和Ia型超新星测量时,提供了显著不一致的值。这种不一致是否暗示新物理或测量中的某些问题,仍在争论中;但显然需要新的独立宇宙学探针来提供额外的证据以解决这个谜团。本章介绍了宇宙计时器方法,这是一种新兴的宇宙学探针,可以提供与宇宙学模型无关的宇宙膨胀历史估计。该方法基于这样一个事实:宇宙的膨胀速率可以直接从测量宇宙在两个不同红移之间的年龄变化中推导出来,即通过估计年龄-红移关系的斜率。首先,将讨论该方法的主要组成部分,介绍涉及的主要方程以及如何从观测量中估计所需量。然后,将介绍如何可靠地选择一组示踪体来连贯地映射宇宙的年龄演化。接下来,将回顾不同方法来稳健地测量一个群体的微分年龄,这是该方法中涉及的基本量。最后,将介绍获得的主要测量结果,为未来调查提供预测,并讨论这些数据如何为解决哈勃常数危机提供有用的反馈。

英文摘要:

Twenty years after the discovery that the expansion of the Universe is accelerating, a new finding is now challenging our understanding of the cosmos. Recent studies have shown that the Hubble constant, the speed of expansion measured today, provides values in significant tension when measured from the Cosmic Microwave Background in the primordial Universe or from Cepheids and Supernovae Type Ia in the local Universe. Whether this tension is hinting towards new physics or some issue in the measurements, is still under debate; but it is clearly calling for new independent cosmological probes to provide additional pieces of evidence to solve this puzzle. This chapter introduces the method of cosmic chronometers, a new emerging cosmological probe that can provide cosmology-independent estimates of the Universe's expansion history. This method is based on the fact that the expansion rate of the Universe can be directly derived from measuring how much the Universe has changed in age between two different redshifts, i.e. by estimating the slope of the age--redshift relation. First, the main ingredients of the method will be discussed, presenting the main equations involved and how to estimate from the observables the needed quantities. After, it will be presented how to reliably select a sample of tracers to map the age evolution of the Universe coherently. Next, different methods to robustly measure the differential age of a population, the fundamental quantity involved in the method, will be reviewed. Finally, the main measurements obtained will be presented, providing forecasts for future surveys and discussing how these data can provide useful feedback to address the Hubble tension.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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