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

Regularized Einstein-Gauss-Bonnet theory of gravity in four dimensions is a new attempt to include nontrivial contributions of the 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, Λ0, is ruled out by the current observational value of wde and the observations of gravitational-wave event GW170817 and the gamma-ray burst (GRB) GRB 170817A, as well. For a nonvanishing bare cosmological constant, instead, our results show that the current observation of the speed of gravitational waves (GWs) measured by GW170817 and GRB 170817A would place a constraint on ˜ α , a dimensionless parameter of the theory, as − 7.78 × 10−16 ≤ ˜ α ≤ 3.33 × 10−15 .