Interacting quintessence from a variational approach Part I: algebraic couplings

Abstract

We present a new approach to build models of quintessence interacting with dark or baryonic matter. We use a variational approach for relativistic fluids to realize an effective description of matter fields at the Lagrangian level. The coupling is introduced directly in the action by considering a single function mixing the dynamical degrees of freedom of the theory. The resulting gravitational field equations are derived by variations with respect to the independent variables. New interesting phenomenology can be obtained at both small scales, where new screening mechanisms for scalar fields can be realized, and large scales, where one finds an original and rich class of interacting quintessence models. The background cosmology of two of these models is studied in detail using dynamical system techniques. We find a variety of interesting results: for instance, these models contain dark energy dominated late time attractors and scaling solutions, both with early time matter dominated epochs and a possible inflationary origin. In general this new approach provides the starting point for future in depth studies on new interacting quintessence models.

29 pages, 12 figures; updated and slightly extended, matches published version

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Cited by in corpus (6)

• Interacting quintessence from a variational approach Part II: derivative couplings
• Distinguishing interacting dark energy from wCDM with CMB, lensing, and baryon acoustic oscillation data
• Scalar-Fluid interacting dark energy: cosmological dynamics beyond the exponential potential
• Extended Phase Space Analysis of Interacting Dark Energy Models in Loop Quantum Cosmology
• Kinetically coupled dark energy
• Lagrangian description of cosmic fluids: mapping dark energy into unified dark energy