Large-scale structure with superhorizon isocurvature dark energy

Abstract

The standard cosmological model assumes a homogeneous and isotropic universe as the background spacetime on large scales called the cosmological principle. However, some observations suggest the possibility of an inhomogeneous and anisotropic universe at large scales. In this paper, we investigate a model of the universe with random inhomogeneities and anisotropies on very large scales, motivated by the supercurvature dark energy model in Nan et al. [Phys. Rev. D 99, 103512 (2019)]. In this model, the authors introduced a scalar field with $\mathcal{O}(1)$ inhomogeneities on a scale sufficiently larger than the current horizon scale (superhorizon scale), and the potential energy of the scalar field explains the accelerating expansion, with slight deviations from the cosmological principle. We aim at clarifying the theoretical prediction on the large-scale structure (LSS) of the matter component in this model. Based on the work on the superhorizon scale fluctuations (superhorizon mode) presented in Nan and Yamamoto [Phys. Rev. D 105, 063518 (2022)], we derive the equations that the perturbative components to the LSS obey as a generalization of the cosmological perturbations theory, which is solved to find the influence of the dark energy inhomogeneities on the formation of the LSS. Finally, we show that the model can be consistent with observations by comparing the ${\sigma }_8$ predicted by the numerical solution of the model with the ${\sigma }_8$ indicated by observations such as Planck and SDSS.

24 pages, 4 figures

References in corpus (13)

• The String Landscape and the Swampland
• Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
• New Extraction of the Cosmic Birefringence from the Planck 2018 Polarization Data
• 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
• The Weak Lensing Signal and the Clustering of BOSS Galaxies II: Astrophysical and Cosmological Constraints
• Separate Universe Simulations
• Constraints on cosmic hemispherical power anomalies from quasars
• Super-Sample Signal
• Viscous Dark Energy In Bianchi Type V Space-Time
• CMASS galaxy sample and the ontological status of the cosmological principle
• Large-scale inhomogeneity of dark energy produced in the ancestor vacuum
• Dark energy model with very large-scale inhomogeneity