Intrinsic Dipole Anisotropies and the Hubble Tension: A Unified Theoretical Framework for Correlated Large-Scale Modes

Abstract The standard ΛCDM cosmological model assumes that primordial perturbations are statistically isotropic and uncorrelated in fourier space. However, recent observations challenge this fundamental tenet, specifically the anomalously large matter dipole detected in the CatWISE2020 quasar catalog (d ∼ 0.016) and the persistent tension in the Hubble constant (H0) measurements. This paper presents a theoretical framework, which relaxes the assumption of mode independence by introducing a wavenumber dependent angular correlation function, C(k, k′). We derive a generalized master equation for the dipole variance, demonstrating that the coherent addition of large-scale modes, governed by an exponential correlation scale ℓc can naturally enhance the intrinsic dipole to match observational excesses without violating CMB constraints. Furthermore, we show that this coherence increases the variance of superhorizon monopole fluctuations, thereby rendering the local 9 % deviation in H0 a statistically probable realization of the cosmic variance. Extending this framework, we demonstrate that the coherent addition of long-wavelength modes amplifies the velocity-field variance, naturally reproducing the unexpectedly large ultra-large-scale bulk flows observed in the CosmicFlows-4 catalog. Finally, we show that correlation-enhanced super-sample covariance induces coherent geometric dilations that subtly warp the inferred distance-redshift relation. This variance enhancement can partially contribute to the DESI-reported shifts in Alcock-Páczyński parameters, providing a ΛCDM-consistent reinterpretation of the apparent preference for dynamical dark energy.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2026-04-13
DOI
https://doi.org/10.1093/mnras/stag582
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
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article

Intrinsic Dipole Anisotropies and the Hubble Tension: A Unified Theoretical Framework for Correlated Large-Scale Modes

Akash Gandhi
Monthly Notices of the Royal Astronomical Society
Galaxies: Formation, Evolution, Phenomena
article

Intrinsic Dipole Anisotropies and the Hubble Tension: A Unified Theoretical Framework for Correlated Large-Scale Modes

Akash Gandhi
article en

Abstract

Abstract The standard ΛCDM cosmological model assumes that primordial perturbations are statistically isotropic and uncorrelated in fourier space. However, recent observations challenge this fundamental tenet, specifically the anomalously large matter dipole detected in the CatWISE2020 quasar catalog (d ∼ 0.016) and the persistent tension in the Hubble constant (H0) measurements. This paper presents a theoretical framework, which relaxes the assumption of mode independence by introducing a wavenumber dependent angular correlation function, C(k, k′). We derive a generalized master equation for the dipole variance, demonstrating that the coherent addition of large-scale modes, governed by an exponential correlation scale ℓc can naturally enhance the intrinsic dipole to match observational excesses without violating CMB constraints. Furthermore, we show that this coherence increases the variance of superhorizon monopole fluctuations, thereby rendering the local 9 % deviation in H0 a statistically probable realization of the cosmic variance. Extending this framework, we demonstrate that the coherent addition of long-wavelength modes amplifies the velocity-field variance, naturally reproducing the unexpectedly large ultra-large-scale bulk flows observed in the CosmicFlows-4 catalog. Finally, we show that correlation-enhanced super-sample covariance induces coherent geometric dilations that subtly warp the inferred distance-redshift relation. This variance enhancement can partially contribute to the DESI-reported shifts in Alcock-Páczyński parameters, providing a ΛCDM-consistent reinterpretation of the apparent preference for dynamical dark energy.

Monthly Notices of the Royal Astronomical Society
Indian Institute of Technology Kanpur (IN)
Openalex Percentile: Top 6%
Galaxies: Formation, Evolution, Phenomena
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