Data-driven and almost model-independent reconstruction of modified gravity

Abstract

In this paper, a modified factor μ, 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 fσ 8(z) data points, one finds out a time varying μ at low redshifts. The reconstructed μ implies that more complicated modified gravity beyond the simplest general relativity and the Dvali-Gabadadze-Porrati braneworld model is required.