Exploring the expansion of the universe using the Grüneisen parameter

Abstract

For a perfect fluid, pressure $p$ and energy density $\rho$ are related via the equation of state (EOS) $\omega =p/\rho$, where $\omega$ is the EOS parameter, being its interpretation usually constrained to a numerical value for each universe era. Here, based on the Mie-Grüneisen EOS, we show that $\omega$ is recognized as the effective Grüneisen parameter ${\Gamma }_{eff}$, whose singular contribution, the so-called Grüneisen ratio $\Gamma$, quantifies the barocaloric effect. Our analysis suggests that the negative $p$ associated with dark-energy implies a metastable state and that in the dark-energy-dominated era $\omega$ is time-dependent, which reinforces recent proposals of a time-dependent cosmological constant. Furthermore, we demonstrate that ${\Gamma }_{eff}$ is embodied in the energy-momentum stress tensor in the Einstein field equations, enabling us to analyse, in the frame of an imperfect fluid picture, anisotropic effects of the universe expansion. We propose that upon going from decelerated- to accelerated-expansion, a phase transition-like behavior can be inferred. Yet, our analysis in terms of entropy, $\Gamma$, and a by us adapted version of Avramov/Casalini's model to Cosmology unveil hidden aspects related to the expansion of the universe. Our findings pave the way to interpret cosmological phenomena in connection with concepts of condensed matter Physics via ${\Gamma }_{eff}$.

arXiv comment11 pages, 1 figure, comments are welcome

References in corpus (43)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• An alternative to quintessence
• Phantom Energy and Cosmic Doomsday
• Dark Energy and the Accelerating Universe
• Small-Scale Challenges to the $\Lambda$CDM Paradigm
• Early Dark Energy Can Resolve The Hubble Tension
• Baryon Acoustic Oscillations in the Ly-α forest of BOSS quasars
• Planck evidence for a closed Universe and a possible crisis for cosmology
• Universally diverging Grueneisen parameter and the magnetocaloric effect close to quantum critical points
• Thermodynamical Scaling of the Glass Transition Dynamics
• Generalized Chaplygin gas as a unified scenario of dark matter/energy: observational constraints
• Thermodynamic interpretation of the scaling of the dynamics of supercooled liquids
• Probing cosmic isotropy with a new X-ray galaxy cluster sample through the $L_{\text{X}}-T$ scaling relation
• Phantom thermodynamics
• Generalized Chaplygin gas model: constraints from Hubble parameter versus Redshift Data
• How the huge energy of quantum vacuum gravitates to drive the slow accelerating expansion of the Universe
• Unified dark energy thermodynamics: varying w and the -1-crossing
• The unreasonable effectiveness of equilibrium-like theory for interpreting non-equilibrium experiments
• The Logotropic Dark Fluid as a unification of dark matter and dark energy
• Symmetry of Cosmological Observables, and a High Hubble Constant as an Indicator of a Mirror World Dark Sector
• Anomalous Lattice Response at the Mott Transition in a Quasi-2D Organic Conductor
• The Cosmic Thermal History Probed by Sunyaev-Zeldovich Effect Tomography
• Extended logotropic fluids as unified dark energy models
• Scaling theory of the Mott transition and breakdown of the Grüneisen scaling near a finite-temperature critical end point
• Temperature Evolution Law of Imperfect Relativistic Fluids
• Effective growth of matter density fluctuations in the running LCDM and LXCDM models
• On phantom thermodynamics with negative temperature
• Comparison between the Logotropic and $\Lambda$CDM models at the cosmological scale
• Galaxy cluster's rotation
• Cosmic Rays in the Inner Galaxy and the Diffusion Properties of the Interstellar Medium
• Time-dependent $G$ in Einstein's equations as an alternative to the cosmological constant
• Griffiths-like phase close to the Mott transition
• Vacuum Energy Density Measured from Cosmological Data
• Grüneisen Parameter for Gases
• Inflation and Quintessence: Theoretical Approach of Cosmological Reconstruction
• Enhanced Grüneisen Parameter in Supercooled Water
• Pressure as a Source of Gravity
• Variable cosmological term $\Lambda (t)$
• Unveiling the Physics of the Mutual Interactions in Paramagnets
• Matter Growth in Imperfect Fluid Cosmology
• The RSD Sorting Hat: Unmixing Radial Scales in Projection
• On the Sackur-Tetrode equation in an expanding universe