Results 11 to 20 of about 17,519 (197)
Spatially flat quantum cosmology [PDF]
Classical and Quantum Gravity, 1991 The authors investigate the quantum cosmology of spatially locally homogeneous cosmological models with flat compact spatial surfaces in three and four spacetime dimensions. In (2+1) dimensions the only possible spatial surfaces are the 2-torus and the Klein bottle, whereas in (3+1) dimensions there are ten possible spatial surfaces.
Jorma Louko, P.J. Ruback
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Exact Solution for Flat Scale-Invariant Cosmology [PDF]
Revista Mexicana de Astronomía y Astrofísica, 2017 An exact solution for the spatially flat scale-invariant cosmology, recently proposed by Maeder (2017a) is deduced. No deviation from the numerical solution was detected. The exact solution yields transparency for the dynamical equations, and faster cosmological constraints may be performed.
J. F. Jesus
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Islands in flat-space cosmology [PDF]
Physical Review D, 2021 Flat-space cosmologies (FSC) are solutions to three dimensional theories of gravity without cosmological constant that have cosmological horizons. A detector located near the time-like singularity of the spacetime can absorb Hawking modes that are created near the horizon.
Sanam Azarnia +3 more
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KiDS-1000 Cosmology: Constraints beyond flat ΛCDM [PDF]
Astronomy & Astrophysics, 2021 We present constraints on extensions to the standard cosmological model of a spatially flat Universe governed by general relativity, a cosmological constant (Λ), and cold dark matter (CDM) by varying the spatial curvature ΩK, the sum of the neutrino masses ∑mν, the dark energy equation of state parameter w, and the Hu-Sawicki f(R) gravity fR0 parameter.
Tilman Tröster +28 more
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Kinematic Cosmology in Conformally Flat Spacetime [PDF]
The Astrophysical Journal, 1998 In a recent series of papers Endean examines the properties of spatially homogeneous and isotropic (FLRW) cosmological models filled with dust in the ``conformally flat spacetime presentation of cosmology'' (CFS cosmology). This author claims it is possible to resolve a certain number of the difficulties the standard model exhibits when confronted to ...
Laurent Querella
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Higher-spin flat space cosmologies with soft hair [PDF]
Journal of High Energy Physics, 2017 We present and discuss near horizon boundary conditions for flat space higher-spin gravity in three dimensions. As in related work our boundary conditions ensure regularity of the solutions independently of the charges. The asymptotic symmetry algebra is given by a set of $\hat{\mathfrak{u}}(1)$ current algebras.
Martin Ammon +4 more
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Holography of 3D Flat Cosmological Horizons [PDF]
Physical Review Letters, 2013 We provide a first derivation of the Bekenstein-Hawking entropy of 3d flat cosmological horizons in terms of the counting of states in a dual field theory. These horizons appear in the shifted-boost orbifold of R^{1,2}, the flat limit of non-extremal rotating BTZ black holes.
Bagchi, Arjun +3 more
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Energy Conservation in Flat FRW Cosmology [PDF]
, 2009 The consequence of energy conservation in the flat Friedmannn-Robertson-Walker (FRW) cosmology is a strictly positive accelerating expansion. A mechanism is proposed for this expansion due to the effect of the attractive (negative) gravitational potential of matter as it is being included within the expanding horizon, and the offsetting work of metric ...
Steven Maxson
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Scalar fields and 3D flat space cosmologies [PDF]
Journal of High Energy PhysicsAbstract Flat Space Cosmologies (FSC) are time-dependent solutions in Einstein gravity in three-dimensional (3D) spacetimes with zero cosmological constant. These are orbifolds of 3D flat space that have a cosmological horizon and can be thought of as analogs of the Banados-Tietelboim-Zanelli (BTZ) black holes of AdS3.
Arjun Bagchi +3 more
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CORRESPONDENCE BETWEEN DGP BRANE COSMOLOGY AND 5D RICCI-FLAT COSMOLOGY [PDF]
Modern Physics Letters A, 2008 We discuss the correspondence between the DGP brane cosmology and 5D Ricci-flat cosmology by letting their metrics equal each other. By this correspondence, a specific geometrical property of the arbitrary integral constant I in DGP metric is given and it is related to the curvature of 5D bulk.
Ping, Yongli, Xu, Lixin, Liu, Hongya
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