The Integrated Sachs-Wolfe Effect in 4D Einstein-Gauss-Bonnet Gravity

TL;DR

This study investigates the integrated Sachs-Wolfe effect within a novel 4D Einstein-Gauss-Bonnet gravity model, revealing an amplified ISW signal compared to the standard Lambda-CDM model, with deviations linked to the coupling parameter.

Contribution

It provides the first detailed analysis of the ISW effect in the 4D Einstein-Gauss-Bonnet gravity, demonstrating its potential to enhance the ISW power spectrum relative to Lambda-CDM.

Findings

The 4D EGB model predicts a higher ISW effect than Lambda-CDM.

The deviation from Lambda-CDM correlates with the coupling parameter β.

The model's predictions are consistent with large-scale structure observations.

Abstract

A novel 4-dimensional Einstein-Gauss-Bonnet (4D EGB) gravity has been proposed that asserts to bypass the Lovelock's theorem and to result in a non-trivial contribution to the gravitational dynamics in four-dimensional spacetime. In this work, we study the integrated Sachs-Wolfe (ISW) effect in the 4D EGB model. For this purpose, we calculate the evolution of the gravitational potential and the linear growth factor as a function of redshift for the 4D EGB model and compare it with the corresponding result obtained from the $\Lambda$-cold dark matter ($\Lambda$CDM) model. We also calculate the ISW-auto power spectrum and the ISW-cross power spectrum as functions of cosmic microwave background (CMB) multipoles for the 4D EGB model and compare those with the one obtained from the $\Lambda$CDM model. To do this, we use the strongest constraint on the coupling parameter proposed for the 4D EGB model. Additionally, to calculate the ISW effect for the 4D EGB model, we employ three large-scale structure surveys from different wavelengths. The results exhibit that the ISW effect in the 4D EGB model is higher than the one obtained from the $\Lambda$CDM model. Hence, we show that the 4D EGB model can amplify the amplitude of the ISW power spectrum, which can be considered as a relative advantage of the 4D EGB model comparing the $\Lambda$CDM one. Also, we indicate that the deviation from the $\Lambda$CDM model is directly proportional to the value of the dimensionless coupling parameter $\beta$.