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Analyzing the Large-Scale Bulk Flow using CosmicFlows4: Increasing Tension with the Standard Cosmological Model

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arxiv 2302.02028 v1 pith:Y6CZHJTU submitted 2023-02-03 astro-ph.CO

Analyzing the Large-Scale Bulk Flow using CosmicFlows4: Increasing Tension with the Standard Cosmological Model

classification astro-ph.CO
keywords bulkflowestimatemodelstandardaccuratelycosmologicaldata
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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We present an estimate of the bulk flow in a volume of radii $150-200h^{-1}$Mpc using the minimum variance (MV) method with data from the CosmicFlows-4 (CF4) catalog. The addition of new data in the CF4 has resulted in an increase in the estimate of the bulk flow in a sphere of radius $150h^{-1}$Mpc relative to the CosmicFlows-3 (CF3). This bulk flow has less than a $0.03\%$ chance of occurring in the Standard Cosmological Model ($\Lambda$CDM) with cosmic microwave background derived parameters. Given that the CF4 is deeper than the CF3, we were able to use the CF4 to accurately estimate the bulk flow on scales of $200h^{-1}$Mpc (equivalent to 266 Mpc for Hubble constant $H_o=75$ km/s/Mpc) for the first time. This bulk flow is in even greater tension with the Standard Model, having less than $0.003\%$ probability of occurring. To estimate the bulk flow accurately, we introduce a novel method to calculate distances and velocities from distance moduli that is unbiased and accurate at all distances. Our results are completely independent of the value of $H_o$.

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Forward citations

Cited by 6 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Multipolar structure of the local expansion rate from incomplete sky data

    astro-ph.CO 2026-07 conditional novelty 6.0

    CF4 data yield a 3.3σ excess dipole in the local expansion-rate fluctuation field at (l,b)=(290°,-4°)±5°, sourced mainly by z∈[0.03,0.05], with quadrupole/octupole consistent with ΛCDM and no multipole-vector alignments.

  2. Expected redshift drift for tilted observers

    astro-ph.CO 2026-05 unverdicted novelty 6.0

    Redshift drift for tilted observers consists of an FLRW background term plus directional corrections from peculiar expansion, projected shear, and acceleration along the line of sight.

  3. New constraints on cosmic anisotropy from galaxy clusters using an improved dipole fitting method

    astro-ph.CO 2026-02 unverdicted novelty 5.0

    Galaxy cluster observations yield two preferred directions with cosmic anisotropy amplitude of about 5.3 times 10 to the minus 4 at roughly 1 sigma overall significance, though higher in the XMM-Newton subsample.

  4. Probing cosmic anisotropy with galaxy clusters and supernovae

    astro-ph.CO 2026-04 unverdicted novelty 4.0

    Analysis of galaxy cluster and supernova data reveals a ~2σ directional variation in the Hubble constant, robust across calibration methods and aligned with the CMB dipole.

  5. Updates on dipolar anisotropy in local measurements of the Hubble constant from Cosmicflows-4

    astro-ph.CO 2025-12 unverdicted novelty 4.0

    Local Hubble constant anisotropy in Cosmicflows-4 data is primarily attributed to peculiar velocities and survey structure rather than cosmic-scale isotropy violation, with limited implications for the Hubble tension.

  6. Dispersion in the Hubble-Lema\^{i}tre constant measurements from gravitational clustering

    astro-ph.CO 2024-07 unverdicted novelty 4.0

    N-body simulations show that peculiar velocities produce large dispersion in local H0 estimates at scales below ~135 Mpc/h, with >5% deviations common up to 40 Mpc/h and a negative correlation with local over-density.