Varying Theory Revisited

• Published in: Gravitation & cosmology Vol. 27; no. 1; pp. 47 - 53
• Main Authors: Fang, YuHong, Singh, Naveen K.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 2021; Springer Nature B.V
• Subjects: Astronomy; Astrophysics and Astroparticles; Classical and Quantum Gravitation; Equations of state; Flux density; Luminosity; Mathematical models; Observations and Techniques; Parameters; Physics; Physics and Astronomy; Quantum Physics; Relativity Theory; Universe
• ISSN: 0202-2893; 1995-0721
• DOI: 10.1134/S0202289321010084

We revisit the variable theory recently developed by Alexander et al. [ 1 , 2 ]. We implement it to explain the current expansion of the Universe. The varying theory reduces one degree of freedom. The varying term (cosmological term) follows the energy density of the Universe. We consider such a theory which does not respect self-dual symmetry. The Bianchi identity enforces the term to be a constant for a theory without torsion. However, torsion can incorporate a varying term in the action. We consider a form of the action which has such a varying term, and the presence of only nonrelativistic matter energy density. We fit the luminosity distance according to the model and compare it with that in the model and find their close behavior. However, we find a current value of matter energy density larger than the critical energy density. Using the supernova data from Union 2.1 compilation, we further consider a different set of parameters, for which becomes close to unity but, however, greater. For this set of parameters, we find a negative value in the effective equation of state, however, the model has a very different pattern of the Hubble parameter from the standard scenario.