Exploring the Growth Index ${\gamma }_L$: Insights from Different CMB Dataset Combinations and Approaches

Abstract

In this study we investigate the growth index ${\gamma }_L$, which characterizes the growth of linear matter perturbations, while analysing different cosmological datasets. We compare the approaches implemented by two different patches of the cosmological solver CAMB: MGCAMB and CAMB_GammaPrime_Growth. In our analysis we uncover a deviation of the growth index from its expected $\Lambda$CDM value of $0.55$ when utilizing the Planck dataset, both in the MGCAMB case and in the CAMB_GammaPrime_Growth case, but in opposite directions. This deviation is accompanied by a change in the direction of correlations with derived cosmological parameters. However, the incorporation of CMB lensing data helps reconcile ${\gamma }_L$ with its $\Lambda$CDM value in both cases. Conversely, the alternative ground-based telescopes ACT and SPT consistently yield growth index values in agreement with ${\gamma }_L=0.55$. We conclude that the presence of the A${}_{\mathrm{lens}}$ problem in the Planck dataset contributes to the observed deviations, underscoring the importance of additional datasets in resolving these discrepancies.

14 pages, 8 figures, 7 tables. V2: Match version accepted for publication in PRD

References in corpus (23)

• Dynamics of dark energy
• Results from a search for dark matter in the complete LUX exposure
• Primordial Black Holes as Dark Matter
• Planck evidence for a closed Universe and a possible crisis for cosmology
• Measurements of the Hubble Constant: Tensions in Perspective
• The Expansion of the Universe is Faster than Expected
• The Megamaser Cosmology Project. XIII. Combined Hubble constant constraints
• Searching for modified growth patterns with tomographic surveys
• Cosmic Microwave Weak lensing data as a test for the dark universe
• Testing gravity with CAMB and CosmoMC
• Hyper Suprime-Cam Year 3 Results: Cosmology from Cosmic Shear Power Spectra
• Arbitrating the $S_8$ discrepancy with growth rate measurements from Redshift-Space Distortions
• The Hubble Constant from Infrared Surface Brightness Fluctuation Distances
• How to optimally parametrize deviations from General Relativity in the evolution of cosmological perturbations
• A combined analysis of the $H_0$ late time direct measurements and the impact on the Dark Energy sector
• Cluster Cepheids with High Precision Gaia Parallaxes, Low Zeropoint Uncertainties, and Hubble Space Telescope Photometry
• Cosmicflows 4: The Calibration of Optical and Infrared Tully-Fisher Relations
• Using The Baryonic Tully-Fisher Relation to Measure $H_o$
• MGCAMB with massive neutrinos and dynamical dark energy
• Health checkup test of the standard cosmological model in view of recent Cosmic Microwave Background Anisotropies experiments
• $S_8$ increases with effective redshift in $\Lambda$CDM cosmology
• New MGCAMB tests of gravity with CosmoMC and Cobaya
• Sweeping Horndeski Canvas: New Growth-Rate Parameterization for Modified-Gravity Theories

Cited by in corpus (12)

• Measuring the reionization optical depth without large-scale CMB polarization
• Planck-PR4 anisotropy spectra show (better) consistency with General Relativity
• Neutrino mass tension or suppressed growth rate of matter perturbations?
• Linear matter density perturbations in the ${\Lambda }_{\mathrm{s}}$CDM model: Examining growth dynamics and addressing the $S_8$ tension
• ${\Lambda }_{\mathrm{s}}$CDM cosmology from a type-II minimally modified gravity
• Revisiting CPL with sign-switching density: To cross or not to cross the NECB
• Late-time Background Constraints on Linear and Non-linear Interacting Dark Energy after DESI DR2
• Explaining JWST star formation history at $z\sim 17$ by modifying $\Lambda$CDM
• Observational constraints on the growth index parameters in $f(Q)$ gravity
• Inflation in non-local hybrid metric-Palatini gravity
• Crunching, Bouncing, and Cyclical Cosmologies from Dark Sector Interactions
• Joint Curvature and Growth Rate measurements with Supernova Peculiar Velocities and the CMB