Paula Boubel, Matthew Colless, Khaled Said and Lister Staveley-Smith
{"title":"Testing anisotropic Hubble expansion","authors":"Paula Boubel, Matthew Colless, Khaled Said and Lister Staveley-Smith","doi":"10.1088/1475-7516/2025/03/066","DOIUrl":null,"url":null,"abstract":"The cosmological principle asserting the large-scale uniformity of the Universe is a testable assumption of the standard cosmological model. We explore the constraints on anisotropic expansion provided by measuring directional variation in the Hubble constant, H0, derived from differential zeropoint measurements of the Tully-Fisher distance estimator. We fit various models for directional variation in H0 using the Tully-Fisher dataset from the all-sky Cosmicflows-4 catalog. The best-fit dipole variation has an amplitude of 0.063 ± 0.016 mag in the direction (ℓ,b) = (142 ± 30°,52 ± 10°). If this were due to anisotropic expansion it would imply a 3% variation in H0 (i.e. ΔH0 = 2.10 ± 0.53 km s-1 Mpc-1 if H0 = 70 km s-1 Mpc-1) with a significance of 3.9σ. A model including this H0 dipole is only weakly favored relative to a model with a constant H0 and a bulk motion of the volume sampled by Cosmicflows-4 consistent with the standard ΛCDM cosmology. However, we show from simulations that the expected Tully-Fisher data from the WALLABY and DESI surveys should allow detection of a 1% H0 dipole anisotropy at 5.8σ confidence and distinguish it from the typical bulk flow predicted by ΛCDM over the volume of these surveys.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"29 1","pages":""},"PeriodicalIF":5.3000,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Cosmology and Astroparticle Physics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1088/1475-7516/2025/03/066","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
The cosmological principle asserting the large-scale uniformity of the Universe is a testable assumption of the standard cosmological model. We explore the constraints on anisotropic expansion provided by measuring directional variation in the Hubble constant, H0, derived from differential zeropoint measurements of the Tully-Fisher distance estimator. We fit various models for directional variation in H0 using the Tully-Fisher dataset from the all-sky Cosmicflows-4 catalog. The best-fit dipole variation has an amplitude of 0.063 ± 0.016 mag in the direction (ℓ,b) = (142 ± 30°,52 ± 10°). If this were due to anisotropic expansion it would imply a 3% variation in H0 (i.e. ΔH0 = 2.10 ± 0.53 km s-1 Mpc-1 if H0 = 70 km s-1 Mpc-1) with a significance of 3.9σ. A model including this H0 dipole is only weakly favored relative to a model with a constant H0 and a bulk motion of the volume sampled by Cosmicflows-4 consistent with the standard ΛCDM cosmology. However, we show from simulations that the expected Tully-Fisher data from the WALLABY and DESI surveys should allow detection of a 1% H0 dipole anisotropy at 5.8σ confidence and distinguish it from the typical bulk flow predicted by ΛCDM over the volume of these surveys.
期刊介绍:
Journal of Cosmology and Astroparticle Physics (JCAP) encompasses theoretical, observational and experimental areas as well as computation and simulation. The journal covers the latest developments in the theory of all fundamental interactions and their cosmological implications (e.g. M-theory and cosmology, brane cosmology). JCAP''s coverage also includes topics such as formation, dynamics and clustering of galaxies, pre-galactic star formation, x-ray astronomy, radio astronomy, gravitational lensing, active galactic nuclei, intergalactic and interstellar matter.