Results 11 to 20 of about 17,761 (262)
No open or flat bouncing cosmologies in Einstein gravity [PDF]
Journal of High Energy Physics, 2015 We show that bouncing open or flat Friedmann-Robertson-Walker cosmologies are inconsistent with worldsheet string theory to first approximation. Specifically, the Virasoro constraint translates to the null energy condition in spacetime at leading order in the alpha-prime expansion.
Maulik Parikh
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Analytical Fit to the Luminosity Distance for Flat Cosmologies with a Cosmological Constant [PDF]
The Astrophysical Journal Supplement Series, 1999 We present a fitting formula for the luminosity and angular diameter distances in cosmological models with pressureless matter, a cosmological constant, and zero spatial curvature. The formula has a relative error of less than 0.4% for 0.2 < Ω0 < 1 for any redshift and a global relative error of less than 4% for any choice of parameters.
Ue‐Li Pen
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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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The Massive Flat Space Limit of Cosmological Correlators [PDF]
Journal of High Energy PhysicsAbstract Identifying useful flat-space limits for cosmological correlators, where they can be expressed in terms of observables in Minkowski space is nontrivial due to their scale-invariant nature. In recent years, it has been shown that momentum-space correlators encode flat-space amplitudes at specific singularities that emerge ...
Sebastián Céspedes, Sadra Jazayeri
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Classical and Quantum Wormholes in a Flat Λ-Decaying Cosmology [PDF]
International Journal of Theoretical Physics, 2008 We study the classical and quantum wormholes for a flat {\it Euclidean} Friedmann-Robertson-Walker metric with a perfect fluid including an ordinary matter source plus a source playing the role of dark energy (decaying cosmological term). It is shown that classical wormholes exist for this model and the quantum version of such wormholes are consistent ...
F. Darabi
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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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A Lognormal Luminosity Function for SWIRE in Flat Cosmology
Advances in Astrophysics, 2018 The evaluation of the physical parameters or effects such as the luminosity function (LF) or the photometric maximum (PM) for galaxies is routinely modeled by their spectroscopic redshift. Here, we model LF and PM for galaxies by the photometric redshift as given by the Spitzer Wide-Area Infrared Extragalactic (SWIRE) catalog in the framework of a ...
Lorenzo Zaninetti
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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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The cluster abundance in flat and open cosmologies [PDF]
Monthly Notices of the Royal Astronomical Society, 1996 Uuencoded package containing LaTeX file (uses mn.sty) plus 7 postscript figures incorporated using epsf. Total length 10 pages. Final version, to appear MNRAS. COBE comparison changed to 4yr data.
Viana, Pedro T P, Liddle, Andrew R
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An Analytical Approximation of the Luminosity Distance in Flat Cosmologies with a Cosmological Constant [PDF]
Progress of Theoretical Physics, 2012 We present an analytical approximation formula for the luminosity distance in spatially flat cosmologies with dust and a cosmological constant. Apart from the overall factor, the effect of non-zero cosmological constant in our formula is written simply in terms of a rational function.
Adachi, Masaru, Kasai, Masumi
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