Constraining the dark fluid

Abstract

Cosmological observations are normally fit under the assumption that the dark sector can be decomposed into dark matter and dark energy components. However, as long as the probes remain purely gravitational, there is no unique decomposition and observations can only constrain a single dark fluid; this is known as the dark degeneracy. We use observations to directly constrain this dark fluid in a model-independent way, demonstrating in particular that the data cannot be fit by a dark fluid with a single constant equation of state. Parameterizing the dark fluid equation of state by a variety of polynomials in the scale factor $a$, we use current kinematical data to constrain the parameters. While the simplest interpretation of the dark fluid remains that it is comprised of separate dark matter and cosmological constant contributions, our results cover other model types including unified dark energy/matter scenarios.

5 pages, 5 figures incorporated. Updated to new observational data including SHOES determination of H0; new citations added

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Cited by in corpus (28)

• Gaussian Process Cosmography
• The dark degeneracy and interacting cosmic components
• Revisiting Generalized Chaplygin Gas as a Unified Dark Matter and Dark Energy Model
• High-Redshift Cosmography
• The phenomenological approach to modeling the dark energy
• Cosmography beyond standard candles and rulers
• Modified Chaplygin Gas as a Unified Dark Matter and Dark Energy Model and Cosmic Constraints
• Unified dark energy and dark matter from a scalar field different from quintessence
• Extended LCDM: generalized non-minimal coupling for dark matter fluids
• Unified Dark Fluid with Constant Adiabatic Sound Speed and Cosmic Constraints
• Extending the generalized Chaplygin gas model by using geometrothermodynamics
• Bulk viscous cosmology: unified dark matter
• Dark matter from dark energy-baryonic matter couplings
• Non-linear dark energy clustering
• Constraints on a decomposed dark fluid with constant adiabatic sound speed by jointing the geometry test and growth rate after Planck data
• Unified Dark Fluid with Constant Adiabatic Sound Speed: Including Entropic Perturbations
• Properties and uncertainties of scalar field models of dark energy with barotropic equation of state
• The effective field theory of multi-component fluids
• Cosmological dark fluid from five-dimensional vacuum
• Dark energy from Geometrothermodynamics
• Nonstandard approach to gravity for the dark sector of the Universe
• Unified dark fluid with fast transition: including entropic perturbations
• Constraining hybrid potential scalar field cosmological model in Lyra's geometry with recent observational data
• Inhomogeneous and interacting vacuum energy
• Unified dark fluid with null sound speed as an alternative to phantom dark energy
• Dark Coincidences: Small-Scale Solutions with Refracted Gravity and MOND
• Refracted Gravity Solutions from Small to Large Scales
• Scalar perturbation of the viscosity dark fluid cosmological model