Cosmic Dipoles from Large-Scale Structure Surveys

Fuente: arXiv
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Main Authors: Yoo, Jaiyul, Magi, Matteo, Huterer, Dragan
Format: Preprint
Published: 2025
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author Yoo, Jaiyul
Magi, Matteo
Huterer, Dragan
author_facet Yoo, Jaiyul
Magi, Matteo
Huterer, Dragan
contents Large-scale structure surveys can be used to measure the dipole in the cosmic microwave background (CMB), in the luminosity distances inferred from type-Ia supernova observations, and in the spatial distribution of galaxies and quasars. The measurements of these cosmic dipoles appear to be mutually inconsistent, even though they are expected to indicate the common observer velocity. This observational tension may represent a significant challenge to the standard model of cosmology. Here we study in detail what contributes to the cosmic dipoles from CMB, supernova, and galaxy survey in the standard $Λ$CDM model, though our theoretical model can be applied beyond the standard model. While measurements of the cosmic dipoles yield the relative velocities between the source samples and the observer velocity, the motion of the observer is the dominant contribution in the conformal Newtonian gauge, and the intrinsic velocities of the samples fall steeply with increasing redshift of the sources. Hence the cosmic dipoles of CMB, type-Ia supernovae, and galaxies should be aligned but can have different amplitudes. We also clarify several misconceptions that are commonly found in the literature.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08931
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Cosmic Dipoles from Large-Scale Structure Surveys
Yoo, Jaiyul
Magi, Matteo
Huterer, Dragan
Cosmology and Nongalactic Astrophysics
Large-scale structure surveys can be used to measure the dipole in the cosmic microwave background (CMB), in the luminosity distances inferred from type-Ia supernova observations, and in the spatial distribution of galaxies and quasars. The measurements of these cosmic dipoles appear to be mutually inconsistent, even though they are expected to indicate the common observer velocity. This observational tension may represent a significant challenge to the standard model of cosmology. Here we study in detail what contributes to the cosmic dipoles from CMB, supernova, and galaxy survey in the standard $Λ$CDM model, though our theoretical model can be applied beyond the standard model. While measurements of the cosmic dipoles yield the relative velocities between the source samples and the observer velocity, the motion of the observer is the dominant contribution in the conformal Newtonian gauge, and the intrinsic velocities of the samples fall steeply with increasing redshift of the sources. Hence the cosmic dipoles of CMB, type-Ia supernovae, and galaxies should be aligned but can have different amplitudes. We also clarify several misconceptions that are commonly found in the literature.
title Cosmic Dipoles from Large-Scale Structure Surveys
topic Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2507.08931