Differential cosmic expansion and the Hubble flow anisotropy

Abstract

The Universe on scales $10-100h^{-1}$ Mpc is dominated by a cosmic web of voids, filaments, sheets and knots of galaxy clusters. These structures participate differently in the global expansion of the Universe: from non-expanding clusters to the above average expansion rate of voids. In this paper we characterize Hubble expansion anisotropies in the COMPOSITE sample of 4534 galaxies and clusters. We concentrate on the dipole and quadrupole in the rest frame of the Local Group. These both have statistically significant amplitudes. These anisotropies, and their redshift dependence, cannot be explained solely by a boost of the Local Group in the Friedmann-Lemaître-Robertson-Walker (FLRW) model which expands isotropically in the rest frame of the cosmic microwave background (CMB) radiation. We simulate the local expansion of the Universe with inhomogeneous Szekeres models, which match the standard FLRW model on $>100h^{-1}$ Mpc scales but exhibit nonkinematic relativistic differential expansion on small scales. We restrict models to be consistent with observed CMB temperature anisotropies, while simultaneously fitting the redshift variation of the Hubble expansion dipole. We include features to account for both the Local Void and the "Great Attractor". While this naturally accounts for the Hubble expansion and CMB dipoles, the simulated quadrupoles are smaller than observed. Further refinement to incorporate additional structures may improve this. This would enable a test of the hypothesis that some large angle CMB anomalies result from failing to treat the relativistic differential expansion of the background geometry, a natural feature of solutions to Einstein's equations not included in the current standard model of cosmology.

32 pages, 4 figures, v3 - clarifications made, version accepted by JCAP

References in corpus (25)

• Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
• Cosmological parameters from the comparison of peculiar velocities with predictions from the 2M++ density field
• Cosmic clocks, cosmic variance and cosmic averages
• Exact solution to the averaging problem in cosmology
• Reconstructed Density and Velocity Fields from the 2MASS Redshift Survey
• Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies I
• Power asymmetry in WMAP and Planck temperature sky maps as measured by a local variance estimator
• CMB anisotropies seen by an off-center observer in a spherically symmetric inhomogeneous universe
• Scale dependence of cosmological backreaction
• Szekeres Swiss-Cheese model and supernova observations
• Anti-lensing: the bright side of voids
• Minivoids in the Local Volume
• Anisotropy in the Hubble constant as observed in the HST Extragalactic Distance Scale Key Project results
• The Szekeres Swiss Cheese model and the CMB observations
• Cosmic Bulk Flow and the Local Motion from Cosmicflows-2
• Absence of self-averaging and of homogeneity in the large scale galaxy distribution
• Cosmic spherical void via coarse-graining and averaging non-spherical structures
• Ricci focusing, shearing, and the expansion rate in an almost homogeneous Universe
• Evidence for an environment-dependent shift in the baryon acoustic oscillation peak
• Multiple non-spherical structures from the extrema of Szekeres scalars
• Studying the precision of ray tracing techniques with Szekeres models
• Methods for studying the accuracy of light propagation in N-body simulations
• Coarse-grained description of cosmic structure from Szekeres models
• The Great Attractor and the Shapley Concentration
• CMB dipoles and other low-order multipoles in the quasispherical Szekeres model

Cited by in corpus (35)

• In the Realm of the Hubble tension $-$ a Review of Solutions
• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• Is the Observable Universe Consistent with the Cosmological Principle?
• Cosmological implications of the anisotropy of ten galaxy cluster scaling relations
• Multipole decomposition of the general luminosity distance 'Hubble law' -- a new framework for observational cosmology
• Model-independent analyses of non-Gaussianity in Planck CMB maps using Minkowski Functionals
• Relativistic numerical cosmology with Silent Universes
• Luminosity distance and anisotropic sky-sampling at low redshifts: a numerical relativity study
• Inhomogeneous cosmology and backreaction: Current status and future prospects
• An effective description of Laniakea: impact on cosmology and the local determination of the Hubble constant
• Is there evidence for anomalous dipole anisotropy in the large-scale structure?
• The KBC Void: Consistency with Supernovae Type Ia and the Kinematic SZ Effect in a $\Lambda$LTB Model
• Non-Spherical Szekeres models in the language of Cosmological Perturbations
• Exploring cosmic origins with CORE: effects of observer peculiar motion
• Cosmological backreaction within the Szekeres model and emergence of spatial curvature
• Cosmological foundations revisited with Pantheon+
• Symmetry and Equivalence in Szekeres Models
• Frames of most uniform Hubble flow
• Baryon acoustic oscillation methods for generic curvature: Application to the SDSS-III Baryon Oscillation Spectroscopic Survey
• An Anisotropic Model for the Universe
• Non-comoving Cold Dark Matter in a $\Lambda$CDM background
• A novel approach to cosmological non-linearities as an effective fluid
• The background Friedmannian Hubble constant in relativistic inhomogeneous cosmology and the age of the Universe
• Frame Rotation in the Szekeres Spacetimes
• Angular distribution of cosmological parameters as a probe of inhomogeneities: a kinematic parametrisation
• Black hole formation from the gravitational collapse of a non-spherical network of structures
• Is there a dynamical tendency in H0 with late time measurements?
• First investigation of void statistics in numerical relativity simulations
• Is the local Hubble flow consistent with concordance cosmology?
• Comment on "Hubble flow variations as a test for inhomogeneous cosmology"
• The model of the local Universe in the framework of the second-order perturbation theory
• Second-order dust perturbations of the non-flat FLRW model with the positive cosmological constant
• Confirming the uniformity of the Hubble flow with Pantheon+ Supernovae
• An effective $\mathbf{\Lambda }$-Szekeres modelling of the local Universe with Cosmicflows-4
• Rotation, Embedding and Topology for the Szekeres Geometry