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We report unbiased AI measurements of the fine structure constant $\alpha$ in two proximate absorption regions in the spectrum of the quasar HE0515$-$4414. The data are high resolution, high signal to noise, and laser frequency comb…

宇宙学与河外天体物理 · 物理学 2025-03-18 John K. Webb , Chung-Chi Lee , Dinko Milakovic , Victor V. Flambaum , Vladimir A. Dzuba , Joao Magueijo

(abridged) We present a new analysis of a large sample of quasar absorption-line spectra obtained using UVES (the Ultraviolet and Visual Echelle Spectrograph) on the VLT (Very Large Telescope) in Chile. In the VLT sample (154 absorbers), we…

Testing possible variations in fundamental constants of nature is a crucial endeavor in observational cosmology. This paper investigates potential cosmological variations in the fine structure constant ($\alpha$) through a non-parametric…

宇宙学与河外天体物理 · 物理学 2024-10-30 Marcelo Ferreira , Rodrigo F. L. Holanda , Javier E. Gonzalez , L. R. Colaço , Rafael C. Nunes

Recent updated results of quasar spectra suggested a 3.9$\sigma$ significance of spatial variation of the fine-structure constant. Theoretically, it is important to examine whether the fine-structure constant, as a fundamental constant in…

广义相对论与量子宇宙学 · 物理学 2020-11-17 Zhe Chang , Qing-Hua Zhu

Inspired by the string axiverse idea, it has been suggested that the recent transition from decelerated to accelerated cosmic expansion is driven by an axion-like quintessence field with a sub-Planckian decay constant. The scenario requires…

宇宙学与河外天体物理 · 物理学 2016-07-05 Razieh Emami , Daniel Grin , Josef Pradler , Alvise Raccanelli , Marc Kamionkowski

Comparison of quasar absorption line spectra with laboratory spectra provides a precise probe for variability of the fine structure constant, alpha, over cosmological time-scales. We constrain variation in alpha in 21 Keck/HIRES Si IV…

天体物理学 · 物理学 2009-08-18 M. T. Murphy , J. K. Webb , V. V. Flambaum , J. X. Prochaska , A. M. Wolfe

Development of fundamental physics relies on the constancy of various fundamental quantities such as the fine structure constant. Detecting or constraining the possible time variations of these fundamental physical quantities is an…

天体物理学 · 物理学 2009-11-10 H. Chand , R. Srianand , P. Petitjean , B. Aracil

We relate possible cosmological variations in the mass ratio mu \equiv m_p/m_e and the fine structure constant alpha to long-range composition-dependent forces mediated by a scalar field. The differential acceleration eta in Eotvos-type…

高能物理 - 唯象学 · 物理学 2010-10-27 Thomas Dent

Astrophysical tests of the stability of fundamental couplings, such as the fine-structure constant $\alpha$, are a powerful probe of new physics. Recently these measurements, combined with local atomic clock tests and Type Ia supernova and…

宇宙学与河外天体物理 · 物理学 2016-01-13 C. J. A. P. Martins , A. M. M. Pinho , P. Carreira , A. Gusart , J. López , C. I. S. A. Rocha

We show how the combination of observations related to strong gravitational lensing and stellar dynamics in ellipticals offers a new way to measure the cosmological matter and dark-energy density parameters. A gravitational lensing estimate…

天体物理学 · 物理学 2009-11-13 C. Grillo , M. Lombardi , G. Bertin

We explore a possible time variation of the fine structure constant ($\alpha \equiv e^2/\hbar c$) using the Sunyaev-Zel'dovich effect measurements of galaxy clusters along with their X-ray observations. Specifically, the ratio of the…

宇宙学与河外天体物理 · 物理学 2021-11-24 Zhi-E Liu , Wen-Fei Liu , Tong-Jie Zhang , Zhong-Xu Zhai , Kamal Bora

The redshift drift is a model-independent probe of fundamental cosmology, but choosing a fiducial model one can also use it to constrain the model parameters. We compare the constraining power of redshift drift measurements by the Extremely…

宇宙学与河外天体物理 · 物理学 2021-09-01 J. Esteves , C. J. A. P. Martins , B. G. Pereira , C. S. Alves

We describe a rigorous construction, using matched asymptotic expansions, which establishes under very general conditions that local terrestrial and solar-system experiments will measure the effects of varying `constants' of Nature…

广义相对论与量子宇宙学 · 物理学 2011-07-19 Douglas J. Shaw , John D. Barrow

Searches for variations of fundamental constants require accurate measurement errors. There are several potential sources of errors and quantifying each one accurately is essential. This paper addresses one source of uncertainty relating to…

天体物理仪器与方法 · 物理学 2022-12-02 Chung-Chi Lee , John K. Webb , Darren Dougan , Vladimir A. Dzuba , Victor V. Flambaum

Strong lensing time delay measurements provide a valuable and almost model-independent tool for cosmological investigations. In this work we recognize that they also carry information on the strength of the gravitational coupling at the…

宇宙学与河外天体物理 · 物理学 2020-09-11 Leonardo Giani , Emmanuel Frion

Laboratory experiments to explore plasma conditions and stimulated particle acceleration can illuminate aspects of the cosmic particle acceleration process. Here we discuss the cosmic-ray candidate source object variety, and what has been…

高能天体物理现象 · 物理学 2009-12-15 Roland Diehl

We present a detailed analysis of present and future Cosmic Microwave Background constraints of the value of the fine-structure constant, $\alpha$. We carry out a more detailed analysis of the WMAP first-year data, deriving state-of-the-art…

天体物理学 · 物理学 2008-11-26 G. Rocha , R. Trotta , C. J. A. P. Martins , A. Melchiorri , P. P. Avelino , R. Bean , P. T. P. Viana

We study the $\Lambda(\alpha)$CDM models with $\Lambda(\alpha)$ being a function of the time-varying fine structure constant $\alpha$. We give a close look at the constraints on two specific $\Lambda(\alpha)$CDM models with one and two…

宇宙学与河外天体物理 · 物理学 2018-09-13 Jin-Jun Zhang , Lu Yin , Chao-Qiang Geng

We search for transient variations of the fine structure constant using data from a European network of fiber-linked optical atomic clocks. By searching for coherent variations in the recorded clock frequency comparisons across the network,…

In this paper, we obtain new measurements of the angular homogeneity scale ($\theta_H$) from the BOSS DR12 and eBOSS DR16 catalogs of Luminous Red Galaxies of the Sloan Digital Sky Survey. Considering the flat $\Lambda$CDM model, we use the…

宇宙学与河外天体物理 · 物理学 2025-07-15 Xiaoyun Shao , Carlos A. P. Bengaly , Rodrigo S. Gonçalves , Gabriela C. Carvalho , Jailson Alcaniz