Special Issue "Cosmology and Extragalactic Astronomy"

A special issue of Symmetry (ISSN 2073-8994).

Deadline for manuscript submissions: 22 April 2020.

Special Issue Editor

Prof. Vasileios Oikonomou
E-Mail Website
Guest Editor
Physics Department, Aristotle University of Thessaloniki, Greece
Interests: Cosmology, Inflationary Cosmology, Modified Theories of Gravity, Physics of the Early Universe, Dark Energy, Dark Matter, Supersymmetry, Mathematical Physics, High Energy Physics, Theoretical Physics, Epistemic Game Theory, Game Theory
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Special Issue Information

Dear Colleagues,

The striking observational data coming from the Planck mission and from the LIGO-VIRGO experiments have stimulated theoretical astrophysicists and cosmologists to focus more on the realistic models that describe our Universe on a local and global scale. The theoretical tools available offer a fertile ground for model building, and the quest is to find a viable description of our Universe. For this Special Issue, we invite specialists that are active in the fields of theoretical cosmology, theoretical astrophysics, and galactic-extra-galactic astronomy to contribute their latest insights in the form of a review or original research paper, in order to provide up to date theoretical presentations of realist models of our Universe, at both large and local scales.

Prof. Vasileios Oikonomou
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 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. 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 1400 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

  • modified gravity
  • cosmology
  • theoretical astrophysics
  • extragalactic astronomy
  • astronomy

Published Papers (2 papers)

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Research

Open AccessArticle
The Gross–Pitaevskii Equation with a Nonlocal Interaction in a Semiclassical Approximation on a Curve
Symmetry 2020, 12(2), 201; https://doi.org/10.3390/sym12020201 - 01 Feb 2020
Abstract
We propose an approach to constructing semiclassical solutions for the generalized multidimensional Gross–Pitaevskii equation with a nonlocal interaction term. The key property of the solutions is that they are concentrated on a one-dimensional manifold (curve) that evolves over time. The approach reduces the [...] Read more.
We propose an approach to constructing semiclassical solutions for the generalized multidimensional Gross–Pitaevskii equation with a nonlocal interaction term. The key property of the solutions is that they are concentrated on a one-dimensional manifold (curve) that evolves over time. The approach reduces the Cauchy problem for the nonlocal Gross–Pitaevskii equation to a similar problem for the associated linear equation. The geometric properties of the resulting solutions are related to Maslov’s complex germ, and the symmetry operators of the associated linear equation lead to the approximation of the symmetry operators for the nonlocal Gross–Pitaevskii equation. Full article
(This article belongs to the Special Issue Cosmology and Extragalactic Astronomy)
Open AccessArticle
Gravitational Instability Caused by the Weight of Heat
Symmetry 2019, 11(12), 1435; https://doi.org/10.3390/sym11121435 - 21 Nov 2019
Cited by 1
Abstract
Thermal energy points towards a disordered, completely uniform state act to counter gravity’s tendency to generate order and structure through gravitational collapse. It is, therefore, expected to contribute to the stabilization of a self-gravitating, classical ideal gas over collapse. However, I identified an [...] Read more.
Thermal energy points towards a disordered, completely uniform state act to counter gravity’s tendency to generate order and structure through gravitational collapse. It is, therefore, expected to contribute to the stabilization of a self-gravitating, classical ideal gas over collapse. However, I identified an instability that always occurs at sufficiently high energies: the high-energy or relativistic gravothermal instability. I argue here that this instability presents an analogous core–halo structure as its Newtonian counterpart, the Antonov instability. The main difference is that in the former case the core is dominated by the gravitation of thermal energy and not rest mass energy. A relativistic generalization of Antonov’s instability—the low-energy gravothermal instability—also occurs. The two turning points, which make themselves evident as a double spiral of the caloric curve, approach each other as relativistic effects become more intense and eventually merge in a single point. Thus, the high and low-energy cases may be realized as two aspects of a single phenomenon—the gravothermal instability—which involves a core–halo separation and an intrinsic heat flow. Finally, I argue that the core formed during a core-collapse supernova is subject to the relativistic gravothermal instability if it becomes sufficiently hot and compactified at the time of the bounce. In this case, it will continue to collapse towards the formation of a black hole. Full article
(This article belongs to the Special Issue Cosmology and Extragalactic Astronomy)
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