Data-driven and Almost Model-independent Reconstruction of Modified Gravity

Abstract

In this paper, a modified factor $\hat{I}¼$, which characterizes modified gravity in the linear matter density perturbation theory, is reconstructed in a data-driven and almost model-independent way via Gaussian process by using currently available cosmic observations. Utilizing the Pantheon+ SNe Ia samples, the observed Hubble parameter $H(z)$ and the redshift space distortion $f\ddot{I}{ƒ}_8(z)$ data points, one finds out a time varying $\hat{I}¼$ at low redshifts. The reconstructed $\hat{I}¼$ implies that more complicated modified gravity beyond the simplest general relativity and the Dvali-Gabadadze-Porrati braneworld model is required.

14 pages, 3 figures