Theoretical and observational constraints on regularized 4$D$ Einstein-Gauss-Bonnet gravity

TL;DR

This paper investigates constraints on four-dimensional Einstein-Gauss-Bonnet gravity from recent cosmological and gravitational wave observations, finding significant restrictions on model parameters and ruling out certain cases.

Contribution

It provides a detailed analysis of observational and theoretical constraints on regularized 4D Einstein-Gauss-Bonnet gravity, including bounds on key parameters based on recent data.

Findings

Vanishing cosmological constant case is ruled out by current observations.

GW speed measurements constrain the parameter alpha within a narrow range.

Nonzero cosmological constant case remains compatible with observations.

Abstract

Regularized Einstein-Gauss-Bonnet (EGB) theory of gravity in four dimensions is a new attempt to include nontrivial contributions of Gauss-Bonnet term. In this paper, we make a detailed analysis on possible constraints of the model parameters of the theory from recent cosmological observations, and some theoretical constraints as well. Our results show that the theory with vanishing bare cosmological constant, $\Lambda_0$, is ruled out by the current observational value of $w_{de}$, and the observations of GW170817 and GRB 170817A as well. For nonvanishing bare cosmological constant, instead, our results show that the current observation of the speed of GWs measured by GW170817 and GRB 170817A would place a constraints on $\tilde{\alpha}$, a dimensionless parameter of the theory, as $-7.78\times10^{-16}\le \tilde{\alpha} \leq 3.33\times10^{-15}$.