f(R) Gravity in an Ellipsoidal Universe

Abstract

We propose a new model of cosmology based on an anisotropic background and a specific $f(R)$ theory of gravity. It is shown that field equations of $f(R)$ gravity in a Bianchi type I background give rise to a modified Friedmann equation. This model contains two important parameters: $\gamma$ and $\delta$. We, thus, simply call our model $\gamma \delta$CDM. It is distinguished in two important aspects from the $\Lambda$CDM model: firstly, the contribution of different energy densities to the Hubble parameter are weighted with different weights, and then, dependence of energy densities to redshift is modified as well. This unorthodox relation of energy content to Hubble parameter brings forth a new way of interpreting the cosmological history. This solution does not allow the existence of a cosmological constant component, however, a dark energy contribution with dependence on redshift is possible. We tested observational relevance of the new solution by best fitting to different data sets. We found that our model could accommodate the idea of cosmological coupling of black holes.

20 pages, 4 figures, 2 tables. v2: Prior choices are explained. New references added. v3: New references and further comments added. v4: Data analysis is repeated with larger data sets. Conclusions are unchanged. New references added. Final version

References in corpus (28)

• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• Raising the bar: new constraints on the Hubble parameter with cosmic chronometers at z$\sim$2
• Cosmological viability of f(R)-gravity as an ideal fluid and its compatibility with a matter dominated phase
• A population of red candidate massive galaxies ~600 Myr after the Big Bang
• Measurements of the Hubble Constant: Tensions in Perspective
• Two Remarkably Luminous Galaxy Candidates at $z\approx 10-12$ Revealed by JWST
• The Megamaser Cosmology Project. XIII. Combined Hubble constant constraints
• Seven hints that early-time new physics alone is not sufficient to solve the Hubble tension
• Early results from GLASS-JWST. III: Galaxy candidates at z$\sim$9-15
• Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
• Dark Energy: the equation of state description versus scalar-tensor or modified gravity
• On the evolution of the Hubble constant with the SNe Ia Pantheon Sample and Baryon Acoustic Oscillations: a feasibility study for GRB-cosmology in 2030
• Cosmic Microwave Background Quadrupole and Ellipsoidal Universe
• Arbitrating the $S_8$ discrepancy with growth rate measurements from Redshift-Space Distortions
• Probing cosmic isotropy with a new X-ray galaxy cluster sample through the $L_{\text{X}}-T$ scaling relation
• Ellipsoidal Universe Can Solve The CMB Quadrupole Problem
• Anisotropic Cosmological Constant and the CMB Quadrupole Anomaly
• Observational evidence for cosmological coupling of black holes and its implications for an astrophysical source of dark energy
• Constraints on a Bianchi type I spacetime extension of the standard $\Lambda$CDM model
• Evidence of a decreasing trend for the Hubble constant
• High-Redshift Galaxies from Early JWST Observations: Constraints on Dark Energy Models
• $f(R)$ gravity in the Jordan Frame as a Paradigm for the Hubble Tension
• Anisotropy of the Universe via the Pantheon supernovae sample revisited
• Anisotropy in the all-sky distribution of galaxy morphological types
• Do supernovae indicate an accelerating universe?
• Exact cosmological solution of a Scalar-Tensor Gravity theory compatible with the $\Lambda CDM$ model
• Formalizing Anisotropic Inflation in Modified Gravity
• Constraining f(R) models with cosmic chronometers and the HII galaxy Hubble diagram

Cited by in corpus (3)

• Implications of cosmologically coupled black holes for pulsar timing arrays
• Ellipsoidal Universe and Cosmic Shear
• Anisotropic cosmology in $q$-deformed entropic gravity