Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
4.9
2.7
Journals
Symmetry
Special Issues
Symmetries in General Relativity, Gravitation, and Cosmology
share announcement

Symmetries in General Relativity, Gravitation, and Cosmology

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Physics".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 1784

Special Issue Editor

Dr. Ángel Rincón

E-Mail Website
Guest Editor
Departamento de Física, Universidad de Santiago de Chile, Avenida Ecuador 3493, Estación Central, Santiago 9170124, Chile
Interests: general relativity; gravitation and cosmology

Special Issue Information

Dear Colleagues,

General relativity, gravitation, and cosmology are fields where the role of symmetry is quite relevant. Such a property can be used to simplify the treatment of non-trivial problems and help with the obtention of exact solutions. To be more precise, spacetime symmetries were originally used in the study of exact solutions of Einstein’s field equations in the context of general relativity, and subsequently, in alternative theories of gravity. It is well known that there are different symmetries (Killing symmetry, Conformal symmetry, etc.), and only after taking advantage of them can we achieve progress. There are several remarkable examples in which the implementation of the idea of symmetry plays a prominent role. For instance, in black hole physics, the well-known Schwarzschild solution can be easily computed after considering spherical symmetry. Similarly, the famous BTZ black hole takes advantage of circular symmetry to make progress in three dimensions. There are also examples where symmetry is the cornerstone in the cosmological context, e.g., dictating the type of universe to be considered. Thus, in the Special Issue, we would like to focus on the impact of different types of symmetries on black holes and cosmological models.

Dr. Ángel Rincón
Guest Editor

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 submissions that pass pre-check are 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. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). 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

  • general relativity
  • gravitation and cosmology
  • spacetime symmetry

Published Papers (1 paper)

Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

23 pages, 981 KiB  
Article
Study of a Viscous ΛWDM Model: Near-Equilibrium Condition, Entropy Production, and Cosmological Constraints
by Norman Cruz, Esteban González and Jose Jovel
Symmetry 2022, 14(9), 1866; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14091866 - 07 Sep 2022
Cited by 4 | Viewed by 1223
Abstract
Extensions to a ΛDM model have been explored in order to face current tensions that occur within its framework, which encompasses broadening the nature of the dark matter (DM) component to include warmness and a non-perfect fluid description. In this paper, we [...] Read more.
Extensions to a ΛDM model have been explored in order to face current tensions that occur within its framework, which encompasses broadening the nature of the dark matter (DM) component to include warmness and a non-perfect fluid description. In this paper, we investigated the late-time cosmological evolution of an exact solution recently found in the literature, which describes a viscous warm ΛDM model (ΛWDM) with a DM component that obeys a polytropic equation of state (EoS), which experiences dissipative effects with a bulk viscosity proportional to its energy density, with proportionality constant ξ0. This solution has the particularity of having a very similar behavior to the ΛCDM model for small values of ξ0, evolving also to a de Sitter type expansion in the very far future. We explore firstly the thermodynamic consistences of this solution in the framework of Eckart’s theory of non-perfect fluids, focusing on the fulfillment of the two following conditions: (i) the near-equilibrium condition and (ii) the positiveness of the entropy production. We explore the range of parameters of the model that allow to fulfill these two conditions at the same time, finding that a viscous WDM component is compatible with both ones, being in this sense, a viable model from the thermodynamic point of view. Furthermore, we constrained the free parameters of the model with the observational data coming from supernovae Ia (SNe Ia) and the observational Hubble parameter data (OHD), using these thermodynamics analyses to define the best priors for the cosmological parameters related to the warmness and the dissipation of the DM, showing that this viscous ΛWDM model can describe the combined SNe Ia+OHD data in the same way as the ΛCDM model. The cosmological constraint at 3σ CL gives us an upper limit on the bulk viscous constant of order ξ0∼106 Pa·s, which is in agreement with some previous investigations. Our results support that the inclusion of a dissipative WDM, as an extension of the standard cosmological model, leads to a both thermodynamically consistent and properly fitted cosmological evolution. Full article
(This article belongs to the Special Issue Symmetries in General Relativity, Gravitation, and Cosmology)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-1
Back to TopTop