Cosmology with variable parameters and effective equation of state for Dark Energy

Abstract

A cosmological constant, Lambda, is the most natural candidate to explain the origin of the dark energy (DE) component in the Universe. However, due to experimental evidence that the equation of state (EOS) of the DE could be evolving with time/redshift (including the possibility that it might behave phantom-like near our time) has led theorists to emphasize that there might be a dynamical field (or some suitable combination of them) that could explain the behavior of the DE. While this is of course one possibility, here we show that there is no imperative need to invoke such dynamical fields and that a variable cosmological constant (including perhaps a variable Newton's constant too) may account in a natural way for all these features.

LaTeX, 9 pages, 1 figure. Talk given at the 7th Intern. Workshop on Quantum Field Theory Under the Influence of External Conditions (QFEXT 05)

References in corpus (40)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• The Cosmological Constant and Dark Energy
• Type Ia Supernova Discoveries at z>1 From the Hubble Space Telescope: Evidence for Past Deceleration and Constraints on Dark Energy Evolution
• Cosmological parameters from SDSS and WMAP
• Cosmological Imprint of an Energy Component with General Equation of State
• A Phantom Menace? Cosmological consequences of a dark energy component with super-negative equation of state
• Cosmological Constant - the Weight of the Vacuum
• The Case for a Positive Cosmological Lambda-term
• Cosmology and the Fate of Dilatation Symmetry
• An alternative to quintessence
• Phantom Energy and Cosmic Doomsday
• New Constraints on ${\Omega }_M$, ${\Omega }_{\Lambda }$, and w from an Independent Set of Eleven High-Redshift Supernovae Observed with HST
• Dark Energy Constraints from the Cosmic Age and Supernova
• Accelerated Universe from Gravity Leaking to Extra Dimensions
• Late-time cosmology in (phantom) scalar-tensor theory: dark energy and the cosmic speed-up
• Unification of Dark Matter and Dark Energy: the Inhomogeneous Chaplygin Gas
• Can dark energy evolve to the Phantom?
• The final state and thermodynamics of dark energy universe
• Evolution of the Scale Factor with a Variable Cosmological Term
• The State of the Dark Energy Equation of State
• WMAP constraints on low redshift evolution of dark energy
• The case for dynamical dark energy revisited
• Cosmology of the Planck Era from a Renormalization Group for Quantum Gravity
• The scaling evolution of cosmological constant
• On the scaling behavior of the cosmological constant and the possible existence of new forces and new light degrees of freedom
• Variable Cosmological Constant as a Planck Scale Effect
• Running G and Λat low energies from physics at M_X: possible cosmological and astrophysical implications
• Effective equation of state for dark energy: mimicking quintessence and phantom energy through a variable Lambda
• Generalized phantom energy
• Cosmological constraints on the dark energy equation of state and its evolution
• Probing Gravitation, Dark Energy, and Acceleration
• Testing the running of the cosmological constant with Type Ia Supernovae at high z
• Renormalization-group running of the cosmological constant and its implication for the Higgs boson mass in the Standard Model
• Confronting the IR Fixed Point Cosmology with High Redshift Observations
• Dark energy transition between quintessence and phantom regimes - an equation of state analysis
• Renormalization-group running of the cosmological constant and the fate of the universe
• Cosmological constant, renormalization group and Planck scale physics
• The Running of the Cosmological and the Newton Constant controlled by the Cosmological Event Horizon
• Phantom appearance of non-phantom matter

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• Dark energy perturbations and cosmic coincidence
• Density Perturbations for Running Cosmological Constant
• Crossing of the w=-1 barrier in viscous modified gravity
• Quasi-local variables in spherical symmetry: numerical applications to dark matter and dark energy sources
• Cosmic perturbations with running G and Lambda
• The spherical collapse model in time varying vacuum cosmologies
• Composite dark energy: cosmon models with running cosmological term and gravitational coupling
• Dark viscous fluid described by a unified equation of state in cosmology
• Cosmological Constant Problems and Renormalization Group
• A single model of traversable wormholes supported by generalized phantom energy or Chaplygin gas
• Effective growth of matter density fluctuations in the running LCDM and LXCDM models
• Parametrizing the transition to the phantom epoch with Supernovae Ia and Standard Rulers
• Cosmologies with variable parameters and dynamical cosmon: implications on the cosmic coincidence problem
• Could some black holes have evolved from wormholes?
• What is there in the black box of dark energy: variable cosmological parameters or multiple (interacting) components?