Special Issue "Selected Papers from José Plínio Baptista School on Cosmology “The dark sector of the universe”"

A special issue of Universe (ISSN 2218-1997).

Deadline for manuscript submissions: closed (31 May 2019).

Special Issue Editors

Prof. Dr. Winfried Zimdahl
E-Mail Website
Guest Editor
Núcleo Cosmo UFES, Universidade Federal do Espírito Santo (UFES), Campus Goiabeiras, Vitória, ES, Brazil
Interests: cosmology; dark energy
Prof. Dr. Júlio César Fabris
E-Mail Website
Guest Editor
Núcleo Cosmo UFES, Universidade Federal do Espírito Santo (UFES), Campus Goiabeiras, Vitória, ES, Brazil
Interests: cosmology; dark energy; black holes; quantum cosmology

Special Issue Information

Dear Colleagues,

The standard general-relativistic cosmological model relies on the existence of a dark sector with the following two components: dark matter and dark energy. The first one is required in order to understand cosmic structure formation, the second one accounts for the currently observed accelerated expansion of the universe. This standard model fits remarkably well with most observational data. However, so far, both components of the dark sector have escaped any direct detection. This situation gave rise to the appearance of alternatives to general relativity, implying deviations from Einstein's theory of gravitation on cosmological scales.

This Special Issue collects contributions reflecting the current status of our understanding of the cosmological dynamics. It discusses the successes and drawbacks of different cosmological models, as well as the potential alternatives emerging from modified gravity proposals. It is based on the updated thematic lectures delivered during the III José Plínio Baptista School of Cosmology, entitled “The Dark Sector of the Universe” (Pedra Azul, Brazil, September 2016, www.cosmo-ufes.org/jpbcosmo3).

Prof. Dr. Winfried Zimdahl
Prof. Dr. Júlio César Fabris
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Universe is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • cosmology
  • dark energy
  • modified gravity

Published Papers (6 papers)

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Research

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Open AccessArticle
Flavour Composition and Entropy Increase of Cosmological Neutrinos After Decoherence
Universe 2019, 5(10), 203; https://doi.org/10.3390/universe5100203 - 25 Sep 2019
Abstract
We propose that gravitational interactions of cosmic neutrinos with the statistically homogeneous and isotropic fluctuations of space-time lead to decoherence. This working hypothesis, which we describe by means of a Lindblad operator, is applied to the system of two- and three-flavour neutrinos undergoing [...] Read more.
We propose that gravitational interactions of cosmic neutrinos with the statistically homogeneous and isotropic fluctuations of space-time lead to decoherence. This working hypothesis, which we describe by means of a Lindblad operator, is applied to the system of two- and three-flavour neutrinos undergoing vacuum oscillations and the consequences are investigated. As a result of this decoherence we find that the neutrino entropy would increase as a function of initial spectral distortions, mixing angles and charge-parity (CP)-violation phase. Subsequently we discuss the chances to discover such an increase observationally (in principle). We also present the expected flavour composition of the cosmic neutrino background after decoherence is completed. The physics of two- or three-flavour oscillation of cosmological neutrinos resembles in many aspects two- or three-level systems in atomic clocks, which were recently proposed by Weinberg for the study of decoherence phenomena. Full article
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Open AccessArticle
The Geometrical Trinity of Gravity
Universe 2019, 5(7), 173; https://doi.org/10.3390/universe5070173 - 15 Jul 2019
Cited by 21
Abstract
The geometrical nature of gravity emerges from the universality dictated by the equivalence principle. In the usual formulation of General Relativity, the geometrisation of the gravitational interaction is performed in terms of the spacetime curvature, which is now the standard interpretation of gravity. [...] Read more.
The geometrical nature of gravity emerges from the universality dictated by the equivalence principle. In the usual formulation of General Relativity, the geometrisation of the gravitational interaction is performed in terms of the spacetime curvature, which is now the standard interpretation of gravity. However, this is not the only possibility. In these notes, we discuss two alternative, though equivalent, formulations of General Relativity in flat spacetimes, in which gravity is fully ascribed either to torsion or to non-metricity, thus putting forward the existence of three seemingly unrelated representations of the same underlying theory. Based on these three alternative formulations of General Relativity, we then discuss some extensions. Full article
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Open AccessArticle
The Effective Field Theory of Dark Energy Diagnostic of Linear Horndeski Theories After GW170817 and GRB170817A
Universe 2019, 5(6), 138; https://doi.org/10.3390/universe5060138 - 04 Jun 2019
Abstract
We summarize the effective field theory of dark energy construction to explore observable predictions of linear Horndeski theories. We review the diagnostic of these theories on the correlation of the large-scale structure phenomenological functions: the effective Newton constant, the light deflection parameter, and [...] Read more.
We summarize the effective field theory of dark energy construction to explore observable predictions of linear Horndeski theories. We review the diagnostic of these theories on the correlation of the large-scale structure phenomenological functions: the effective Newton constant, the light deflection parameter, and the growth function of matter perturbations. We take this opportunity to discuss the evolution of the bounds the propagation speed of gravitational waves has undergone and use the most restrictive one to update the diagnostic. Full article
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Review

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Open AccessReview
An Introduction to Particle Dark Matter
Universe 2019, 5(10), 213; https://doi.org/10.3390/universe5100213 - 17 Oct 2019
Abstract
We review the features of Dark Matter as a particle, presenting some old and new instructive models, and looking for their physical implications in the early universe and in the process of structure formation. We also present a schematic of Dark Matter searches [...] Read more.
We review the features of Dark Matter as a particle, presenting some old and new instructive models, and looking for their physical implications in the early universe and in the process of structure formation. We also present a schematic of Dark Matter searches and introduce the most promising candidates to the role of Dark Matter particle. Full article
Open AccessReview
Selected Topics in Numerical Methods for Cosmology
Universe 2019, 5(9), 192; https://doi.org/10.3390/universe5090192 - 29 Aug 2019
Abstract
The large amount of cosmological data already available (and in the near future) makes the development of efficient numerical codes necessary. Many software products have been implemented to perform cosmological analyses considering one or few probes. The need of multi-task software is rapidly [...] Read more.
The large amount of cosmological data already available (and in the near future) makes the development of efficient numerical codes necessary. Many software products have been implemented to perform cosmological analyses considering one or few probes. The need of multi-task software is rapidly increasing, in order to combine numerous cosmological probes along with their specificity (e.g., astrophysical descriptions and systematic errors). In this work, we mention some of these libraries, bringing out some challenges they will face in the few-percent error era (on the cosmological parameters). We review some concepts of the standard cosmological model, and examine some specific topics on their implementation, bringing, for example, the discussion on how some quantities are numerically defined in different codes. We also consider implementation differences between public codes, mentioning their advantages/disadvantages. Full article
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Open AccessReview
Observing the Dark Sector
Universe 2019, 5(6), 137; https://doi.org/10.3390/universe5060137 - 04 Jun 2019
Abstract
Despite the observational success of the standard model of cosmology, present-day observations do not tightly constrain the nature of dark matter and dark energy and modifications to the theory of general relativity. Here, we will discuss some of the ongoing and upcoming surveys [...] Read more.
Despite the observational success of the standard model of cosmology, present-day observations do not tightly constrain the nature of dark matter and dark energy and modifications to the theory of general relativity. Here, we will discuss some of the ongoing and upcoming surveys that will revolutionize our understanding of the dark sector. Full article
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