Data reconstruction of the dynamical connection function in f(Q) cosmology

Abstract

We employ Hubble data and Gaussian Processes in order to reconstruct the dynamical connection function in f(Q) cosmology beyond the coincident gauge. In particular, there exist three branches of connections that satisfy the torsionless and curvatureless conditions, parameterized by a new dynamical function γ. We express the redshift dependence of γ in terms of the H(z) function and the f(Q) form and parameters, and then we reconstruct it using 55 H(z) observation data. Firstly, we investigate the case where ordinary conservation law holds, and we reconstruct the f(Q) function, which is very well described by a quadratic correction on top of Symmetric Teleparallel Equivalent of General Relativity. Proceeding to the general case, we consider two of the most studied f(Q) models of the literature, namely the square-root and the exponential one. In both cases we reconstruct γ(z), and we show that according to AIC and BIC information criteria its inclusion is favoured compared to both ΛCDM paradigm, as well as to the same f(Q) models under the coincident gauge. This feature acts as an indication that f(Q) cosmology should be studied beyond the coincident gauge.