Low redshift constraints on energy-momentum-powered gravity models

Abstract

There has been recent interest in the cosmological consequences of energy-momentum-powered gravity models, in which the matter side of Einstein's equations is modified by the addition of a term proportional to some power, $n$, of the energy-momentum tensor, in addition to the canonical linear term. In this work we treat these models as phenomenological extensions of the standard $\Lambda$CDM, containing both matter and a cosmological constant. We also quantitatively constrain the additional model parameters using low redshift background cosmology data that are specifically from Type Ia supernovas and Hubble parameter measurements. We start by studying specific cases of these models with fixed values of $n,$ which lead to an analytic expression for the Friedmann equation; we discuss both their current constraints and how the models may be further constrained by future observations of Type Ia supernovas for WFIRST complemented by measurements of the redshift drift by the ELT. We then consider and constrain a more extended parameter space, allowing $n$ to be a free parameter and considering scenarios with and without a cosmological constant. These models do not solve the cosmological constant problem per se. Nonetheless these models can phenomenologically lead to a recent accelerating universe without a cosmological constant at the cost of having a preferred matter density of around ${\Omega }_M\sim 0.4$ instead of the usual ${\Omega }_M\sim 0.3$. Finally we also briefly constrain scenarios without a cosmological constant, where the single component has a constant equation of state which needs not be that of matter; we provide an illustrative comparison of this model with a more standard dynamical dark energy model with a constant equation of state.

13+2 pages, 12+1 figures; A&A (in press)

References in corpus (6)

• Wide-Field InfrarRed Survey Telescope-Astrophysics Focused Telescope Assets WFIRST-AFTA 2015 Report
• Hubble parameter measurement constraints on the redshift of the deceleration-acceleration transition, dynamical dark energy, and space curvature
• Cosmic dynamics in the era of Extremely Large Telescopes
• Energy-Momentum Squared Gravity
• A Lagrangian description of interacting dark energy
• Dark sectors of the Universe: A Euclid survey approach

Cited by in corpus (5)

• Generalized Energy-Momentum-Squared Gravity in the Palatini Formalism
• Emergent Universe from Energy-Momentum Squared Gravity
• Constraining Energy-Momentum-Squared Gravity by binary pulsar observations
• Cosmological models in scale-independent energy-momentum squared gravity
• Observational constraints on nonlinear matter extensions of general relativity: Separable trace power models