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Universe, Volume 10, Issue 11

November 2024 - 30 articles

Cover Story: In the framework of the analogous Hawking effect, the main contribution of our paper consists in finding, in a two-dimensional model, and in the limit of weak dispersive effects, a complete set of relations between ingoing modes P, N, V entering the horizon, and outgoing modes H, \({\overset{-}{H}}\), \({V^{′}}\) reaching the asymptotic region. This is achieved by deducing, on purely mathematical grounds, the connection formulas without introducing heuristical boundary conditions ad hoc. A general picture for calculating all the interesting amplitudes involved in the scattering matrix is provided. The present framework encompasses many interesting systems involved in experiments (BEC, water, dielectric media). We also provide some insights about the four dimensional case and about exact solutions of the equation involving non-dispersive modes. View this paper
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Articles (30)

  • Article
  • Open Access
3 Citations
1,456 Views
31 Pages

20 November 2024

Schwarzschild and Reissner–Nordstrøm black hole solutions are found in the context of a non-minimal matter–curvature coupling with Weyl connection both in vacuum and in the presence of a cosmological constant-like matter content. T...

  • Article
  • Open Access
2 Citations
1,341 Views
17 Pages

The Properties of an Edge-On Low Surface Brightness Galaxies Sample

  • Tian-Wen Cao,
  • Zi-Jian Li,
  • Pei-Bin Chen,
  • Venu M. Kalari,
  • Cheng Cheng,
  • Gaspar Galaz,
  • Hong Wu and
  • Junfeng Wang

20 November 2024

We analyzed the properties of a sample of edge-on low-surface brightness galaxies, which are referred to as Cao23 ELSBGs. Cao23 ELSBGs exhibit a wide range of luminosities (−22 < Mr < −13) with a mean scale length of 3.19 ± 1...

  • Article
  • Open Access
4 Citations
1,669 Views
22 Pages

19 November 2024

Leveraging the photometric data of the Sloan Digital Sky Survey and the Galaxy Evolution Explorer (GALEX), we construct mean/median spectral energy distributions (SEDs) for unique bright quasars in redshift bins of 0.2 and up to z≃3, after taki...

  • Article
  • Open Access
8 Citations
1,798 Views
19 Pages

Black Holes with a Cloud of Strings and Quintessence in a Non-Linear Electrodynamics Scenario

  • Francinaldo Florencio do Nascimento,
  • Valdir Barbosa Bezerra and
  • Jefferson de Morais Toledo

19 November 2024

We obtain exact black hole solutions to Einstein gravity coupled with a nonlinear electrodynamics field, in the presence of a cloud of strings and quintessence, as sources. The solutions have four parameters, namely m, k, a, and α, correspondin...

  • Review
  • Open Access
1 Citations
1,248 Views
28 Pages

18 November 2024

In the current review, we provide a summary of the recent progress made in the cosmological aspect of extra-dimensional Lovelock gravity. Our review covers a wide variety of particular model/matter source combinations: Einstein–Gauss–Bonn...

  • Article
  • Open Access
1 Citations
1,040 Views
20 Pages

Current Density Induced by a Cosmic String in de Sitter Spacetime in the Presence of Two Flat Boundaries

  • Wagner Oliveira dos Santos,
  • Herondy F. Santana Mota and
  • Eugênio R. Bezerra de Mello

17 November 2024

In this paper, we investigate the vacuum bosonic current density induced by a carrying-magnetic-flux cosmic string in a (D+1)-de Sitter spacetime considering the presence of two flat boundaries perpendicular to it. In this setup, the Robin boundary c...

  • Article
  • Open Access
10 Citations
1,377 Views
16 Pages

Post-Newtonian Effects in Compact Binaries with a Dark Matter Spike: A Lagrangian Approach

  • Diego Montalvo,
  • Adam Smith-Orlik,
  • Saeed Rastgoo,
  • Laura Sagunski,
  • Niklas Becker and
  • Hazkeel Khan

17 November 2024

We apply the Lagrangian method to study the post-Newtonian evolution of a compact binary system with environmental effects, including a dark matter spike, and obtain the resulting gravitational wave emission. This formalism allows one to incorporate...

  • Article
  • Open Access
1 Citations
1,040 Views
11 Pages

15 November 2024

Gravitational waves (GWs) are expected to interact with dark energy and dark matter, affecting their propagation on cosmological scales. To model this interaction, we derive a gauge-invariant effective equation and action valid for all GW polarizatio...

  • Article
  • Open Access
1 Citations
1,850 Views
30 Pages

Sources and Radiations of the Fermi Bubbles

  • Vladimir A. Dogiel and
  • Chung-Ming Ko

12 November 2024

Two enigmatic gamma-ray features in the galactic central region, known as Fermi Bubbles (FBs), were found from Fermi-LAT data. An energy release, (e.g., by tidal disruption events in the Galactic Center, GC), generates a cavity with a shock that expa...

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Universe - ISSN 2218-1997