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Universe, Volume 4, Issue 10

October 2018 - 13 articles

Cover Story: Modelling the present accelerated expansion of the universe without an ad hoc dark energy motivates modified theories of gravity that contain an effective dynamical cosmological constant, causing black holes to be non-asymptotically flat nor stationary. Other fundamental causes include backreaction of Hawking radiation, companions in binary systems, accretion, or quantum corrections. In modified and in Einstein gravity, modelling such dynamical black holes requires a new definition of black hole and the investigation of apparent horizons. Black hole mechanics and thermodynamics become much more challenging and many questions remain unanswered. Cosmological black holes constitute an interesting class of analytical solutions of the field equations of various theories of gravity. Focusing on spherical symmetry, this article reviews these solutions and their apparent horizon histories. View this paper.
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Articles (13)

  • Feature Paper
  • Article
  • Open Access
65 Citations
6,064 Views
15 Pages

Inconsistencies of the New No-Boundary Proposal

  • Job Feldbrugge,
  • Jean-Luc Lehners and
  • Neil Turok

29 September 2018

In previous works, we have demonstrated that the path integral for real, Lorentzian four-geometries in Einstein gravity yields sensible results in well-understood physical situations, but leads to uncontrolled fluctuations when the “no boundary” cond...

  • Article
  • Open Access
4 Citations
3,946 Views
19 Pages

28 September 2018

We propose a cross-correlation method for the searches of ultra-light fields, in particular, with a space network of atomic sensors. The main motivation of the approach is cancellation of uncorrelated noises in the observation data and unique pattern...

  • Article
  • Open Access
34 Citations
4,043 Views
29 Pages

The Vacuum State of Primordial Fluctuations in Hybrid Loop Quantum Cosmology

  • Beatriz Elizaga Navascués,
  • Daniel Martín de Blas and
  • Guillermo A. Mena Marugán

22 September 2018

We investigate the role played by the vacuum of the primordial fluctuations in hybrid Loop Quantum Cosmology. We consider scenarios where the inflaton potential is a mass term and the unperturbed quantum geometry is governed by the effective dynamics...

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Universe - ISSN 2218-1997