Cosmological solutions and growth index of matter perturbations in f(Q) gravity

By Wompherdeiki Khyllep, Andronikos Paliathanasis, J. Dutta. Physical Review D, 2021

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The present work studies one of Einstein’s alternative formulations based on the non-metricity scalar Q generalized as f ( Q ) theory. More specifically, we consider the power-law form of f ( Q ) gravity i.e. f ( Q ) = Q + α Q n . Here, we analyze the behavior of the cosmological model at the background and perturbation level. Using the dynamical system analysis, at the background level, the effective evolution of the model is the same as that of the ΛCDM for | n | < 1. Interestingly, the geometric component of the theory solely determined the late-time acceleration of the Universe. We also examine the integrability of the model by employing the method of singularity analysis. In particular, we find the conditions under which field equations pass the Painlev´e test and hence possess the Painlev´e property. While the equations pass the Painlev´e test in the presence of dust for any value of n , the test is valid after the addition of radiation fluid only for n < 1. Finally, at the perturbation level, the behavior of matter growth index signifies a deviation of the model from the ΛCDM even for | n | < 1. to the matter Lagrangian. As a cosmological application they show that it can represent an alternative approach to dark energy (DE) [13]. Observational constraints on the background behavior of several f ( Q ) models have been performed by testing against various current background data such as Type Ia Supernovae, Pantheon data, Hubble data, etc. [14, 15]. These studies conclude that viable f ( Q ) models correspond to model parameters’ values which resemble the GR-based model viz. the Lambda Cold Dark Matter (ΛCDM) model. Mandal et. al. analyzed the energy conditions to restrict the parameters of the power-law and logarithmic f ( Q ) models

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Oceanography

View Paper: https://www.semanticscholar.org/paper/be1ef01ab838c31994855b9b133803ff42261f72