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Universe, Volume 9, Issue 6

June 2023 - 54 articles

Cover Story: In this study, we reanalyze the running vacuum model (RVM) in full and we find it becomes further buttressed. Using modern cosmological data, namely a compilation of the latest SNIa+BAO+H(z)+LSS+CMB observations, we determine to what extent the RVM provides a high-quality fit that is better than the concordance ΛCDM model, with particular emphasis on its impact on the σ8 and H0 tensions. We utilize the Einstein–Boltzmann system solver CLASS and the Monte Carlo sampler MontePython for the statistical analysis, as well as the statistical DIC criterion to compare the running vacuum against the rigid vacuum (νeff=0). We show that with a tiny amount of vacuum dynamics (νeff≪1), the global fit can improve significantly with respect to the ΛCDM, and the mentioned tensions may subside to inconspicuous levels. View this paper
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Articles (54)

  • Article
  • Open Access
3 Citations
2,986 Views
54 Pages
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Deep Learning of Quasar Lightcurves in the LSST Era

  • Andjelka B. Kovačević,
  • Dragana Ilić,
  • Luka Č. Popović,
  • Nikola Andrić Mitrović,
  • Mladen Nikolić,
  • Marina S. Pavlović,
  • Iva Čvorović-Hajdinjak,
  • Miljan Knežević and
  • Djordje V. Savić
Universe2023, 9(6), 287;https://doi.org/10.3390/universe9060287

11 June 2023

Deep learning techniques are required for the analysis of synoptic (multi-band and multi-epoch) light curves in massive data of quasars, as expected from the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). In this follow-up study, w...

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  • Article
  • Open Access
1 Citations
2,073 Views
17 Pages
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Maxwell Field of a Charge in Hyperbolic Motion

  • Ramón Serrano Montesinos and
  • Juan Antonio Morales-Lladosa
Universe2023, 9(6), 286;https://doi.org/10.3390/universe9060286

10 June 2023

We conduct a detailed study of the electromagnetic field produced by a massive point particle undergoing hyperbolic (uniformly accelerated) motion in Minkowski space-time. Starting from the Liénard–Wiechert solution and using a covariant...

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  • Article
  • Open Access
2,139 Views
14 Pages
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Compact Stars in the vBag Model and Its f-Mode Oscillations

  • Heng-Yi Zhou,
  • Wei Wei and
  • Xia Zhou
Universe2023, 9(6), 285;https://doi.org/10.3390/universe9060285

10 June 2023

Electromagnetic (EM) observations and gravitational wave (GW) measurements enable us to determine the mass and radius of neutron stars (NSs) and their tidal deformability, respectively. These parameters offer valuable insights into the properties of...

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  • Feature Paper
  • Article
  • Open Access
2 Citations
2,285 Views
16 Pages
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Classical Mechanics with Inequality Constraints and Gravity Models with Limiting Curvature

  • Andrei V. Frolov and
  • Valeri P. Frolov
Universe2023, 9(6), 284;https://doi.org/10.3390/universe9060284

10 June 2023

In this paper, we discuss mechanical systems with inequality constraints Φ(q,q˙,...)≤0. We demonstrate how such constraints can be taken into account by proper modification of the action which describes the original unconstrained dynamics...

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  • Article
  • Open Access
2 Citations
1,349 Views
14 Pages
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Homogeneous Cosmological Models in Weyl’s Geometrical Scalar–Tensor Theory

  • Adriano Barros and
  • Carlos Romero
Universe2023, 9(6), 283;https://doi.org/10.3390/universe9060283

10 June 2023

In this paper, we consider homogeneous cosmological solutions in the context of the Weyl geometrical scalar–tensor theory. Firstly, we exhibit an anisotropic Kasner type solution taking advantage of some similarities between this theory and the...

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  • Article
  • Open Access
1,502 Views
34 Pages
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A Variational Approach to Resistive General Relativistic Two-Temperature Plasmas

  • Gregory Lee Comer,
  • Nils Andersson,
  • Thomas Celora and
  • Ian Hawke
Universe2023, 9(6), 282;https://doi.org/10.3390/universe9060282

9 June 2023

We develop an action principle to construct the field equations for dissipative/resistive general relativistic two-temperature plasmas, including a neutrally charged component. The total action is a combination of four pieces: an action for a multifl...

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  • Article
  • Open Access
3 Citations
1,762 Views
19 Pages
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Henneaux–Teitelboim Gauge Symmetry and Its Applications to Higher Gauge Theories

  • Mihailo Đorđević,
  • Tijana Radenković,
  • Pavle Stipsić and
  • Marko Vojinović
Universe2023, 9(6), 281;https://doi.org/10.3390/universe9060281

9 June 2023

When discussing the gauge symmetries of any theory, the Henneaux–Teitelboim transformations are often underappreciated or even completely ignored, due to their on-shell triviality. Nevertheless, these gauge transformations play an important rol...

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  • Article
  • Open Access
6 Citations
2,067 Views
25 Pages
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Modeling the Topside Ionosphere Effective Scale Height through In Situ Electron Density Observations by Low-Earth-Orbit Satellites

  • Alessio Pignalberi,
  • Michael Pezzopane,
  • Tommaso Alberti,
  • Igino Coco,
  • Giuseppe Consolini,
  • Giulia D’Angelo,
  • Paola De Michelis,
  • Fabio Giannattasio,
  • Bruno Nava and
  • Mirko Piersanti
  • + 1 author
Universe2023, 9(6), 280;https://doi.org/10.3390/universe9060280

9 June 2023

In this work, we aim to characterize the effective scale height at the ionosphere F2-layer peak (H0) by using in situ electron density (Ne) observations by Langmuir Probes (LPs) onboard the China Seismo-Electromagnetic Satellite (CSES—01). CSES...

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  • Review
  • Open Access
4 Citations
2,603 Views
29 Pages
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The Central Engine of GRB170817A and the Energy Budget Issue: Kerr Black Hole versus Neutron Star in a Multi-Messenger Analysis

  • Maurice H. P. M. van Putten
Universe2023, 9(6), 279;https://doi.org/10.3390/universe9060279

8 June 2023

Upcoming LIGO–Virgo–KAGRA (LVK) observational runs offer new opportunities to probe the central engines of extreme transient events. Cosmological gamma-ray bursts (GRBs) and core-collapse supernovae (CC-SNe), in particular, are believed t...

Full Article
  • Article
  • Open Access
11 Citations
2,186 Views
16 Pages
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A Wheeler–DeWitt Quantum Approach to the Branch-Cut Gravitation with Ordering Parameters

  • Benno August Ludwig Bodmann,
  • César Augusto Zen Vasconcellos,
  • Peter Otto Hess Bechstedt,
  • José Antonio de Freitas Pacheco,
  • Dimiter Hadjimichef,
  • Moisés Razeira and
  • Gervásio Annes Degrazia
Universe2023, 9(6), 278;https://doi.org/10.3390/universe9060278

8 June 2023

In this contribution to the Festschrift for Prof. Remo Ruffini, we investigate a formulation of quantum gravity using the Hořava–Lifshitz theory of gravity, which is General Relativity augmented by counter-terms to render the theory regula...

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Universe - ISSN 2218-1997
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