Running Vacuum in the Universe: Phenomenological Status in Light of the Latest Observations, and Its Impact on the σ8 and H0 Tensions

Peracaula, Joan Solà; Gómez-Valent, Adrià; Pérez, Javier de Cruz; Moreno-Pulido, Cristian

doi:10.3390/universe9060262

Cited by 32 publications

(7 citation statements)

References 180 publications

(317 reference statements)

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“…[183] for reviews). The latest cosmological data are in good agreement with the RVMs [184,185], while confirming the results of earlier constraints of these models [186][187][188]. The cosmological constant problem of the ΛCDM model can be resolved in the RVMs [189,190], and the H 0 and σ 8 tensions weaken in these models, as can be seen from the data constraints presented in [184,185].…”

Section: Introductionsupporting

confidence: 86%

Observational Constraints on Dynamical Dark Energy Models

Avsajanishvili,

Chitov,

Kahniashvili

et al. 2024

Universe

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Scalar field ϕCDM models provide an alternative to the standard ΛCDM paradigm, while being physically better motivated. Dynamical scalar field ϕCDM models are divided into two classes: the quintessence (minimally and non-minimally interacting with gravity) and phantom models. These models explain the phenomenology of late-time dark energy. In these models, energy density and pressure are time-dependent functions under the assumption that the scalar field is described by the ideal barotropic fluid model. As a consequence of this, the equation of state parameter of the ϕCDM models is also a time-dependent function. The interaction between dark energy and dark matter, namely their transformation into each other, is considered in the interacting dark energy models. The evolution of the universe from the inflationary epoch to the present dark energy epoch is investigated in quintessential inflation models, in which a single scalar field plays a role of both the inflaton field at the inflationary epoch and of the quintessence scalar field at the present epoch. We start with an overview of the motivation behind these classes of models, the basic mathematical formalism, and the different classes of models. We then present a compilation of recent results of applying different observational probes to constraining ϕCDM model parameters. Over the last two decades, the precision of observational data has increased immensely, leading to ever tighter constraints. A combination of the recent measurements favors the spatially flat ΛCDM model but a large class of ϕCDM models is still not ruled out.

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Section: Introductionsupporting

confidence: 86%

Observational Constraints on Dynamical Dark Energy Models

Avsajanishvili,

Chitov,

Kahniashvili

et al. 2024

Universe

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show abstract

“…In the above, V Λ is a constant parameter which plays a role analogous to the cosmological constant while ξ and χ are coupling parameters. Energy exchanges between a nonrelativistic fluid and a vacuum component have been considered in the context of running vacuum models (see [8][9][10][11] and references therein). In this scenario the vacuum component is regarded as a dynamical variable and its fluctuation-which depends on contributions from the quantized matter fields, namely, bosons and fermions-is evaluated from quantum field calculations.…”

Section: Background Modelsmentioning

confidence: 99%

“…Also motivated by quantum field theory considerations [8][9][10][11] the possibility of an interacting vacuum component has been a subject of considerable interest. In the context of black hole formation for instance, it has been shown [12] that a nonsingular collapse of barotropic perfect fluids may give rise to Reissner-Nordström-de Sitter black holes.…”

Section: Introductionmentioning

confidence: 99%

Scalar perturbations in nonsingular universes from interacting vacuum

Alves,

Maier

2024

Class. Quantum Grav.

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In this paper we examine the stability of scalar perturbations in nonsingular models which emerge from an interacting vacuum component. The analysis developed in this paper relies on two phenomenological choices for the energy exchange between a nonrelativistic fluid and a vacuum component. In both scenarios it can be shown that closed models may furnish nonsingular orbits of physical interest in phase space once a decelerated past era is connected to a graceful exit to late-time acceleration. Regarding such configurations as background spacetimes we introducescalar perturbations in order to examine the stability of these models in a high energy domain.We explicitly show that the vacuum perturbation is not an independent variable and diverges asdynamics approaches the bounce. This feature assigns a rather unstable signature to the dynamicsmaking the choices for the energy transfer ill defined at least for nonsingular configurationsat the bounce scale.

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“…a different renormalization procedure. The phenomenological implications of such models have been discussed in [59].…”

Section: Jcap11(2023)030mentioning

confidence: 99%

Cosmic energy density: particles, fields and the vacuum

Armendariz-Picon,

Diez-Tejedor

2023

J. Cosmol. Astropart. Phys.

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We revisit the cosmic evolution of the energy density of a quantized free scalar field and assess under what conditions the particle production and classical field approximations reproduce its correct value. Because the unrenormalized energy-momentum tensor diverges in the ultraviolet, it is necessary to frame our discussion within an appropriate regularization and renormalization scheme. Pauli-Villars avoids some of the drawbacks of adiabatic subtraction and dimensional regularization and is particularly convenient in this context. In some cases, we can predict the evolution of the energy density irrespectively of the quantum state of the field modes. To further illustrate our results we focus however on the in vacuum, the preferred quantum state singled out by inflation, and explore to what extent the latter determines the subsequent evolution of the energy density regardless of the unknown details of reheating. We contrast this discussion with examples of transitions to radiation domination that avoid some of the problems of the one commonly studied in the literature, and point out some instances in which the particle production or the classical field approximations lead to the incorrect energy density. Along the way, we also elaborate on the connection of our analysis to dynamical dark energy models and axion-like dark matter candidates.

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Running Vacuum in the Universe: Phenomenological Status in Light of the Latest Observations, and Its Impact on the σ8 and H0 Tensions

Cited by 32 publications

References 180 publications

Observational Constraints on Dynamical Dark Energy Models

Observational Constraints on Dynamical Dark Energy Models

Scalar perturbations in nonsingular universes from interacting vacuum

Cosmic energy density: particles, fields and the vacuum

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