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  • 1
    Electronic Resource
    Electronic Resource
    Perturbations in inflationary cosmologies with smooth exit (1998)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 39 (1998), S. 5491-5501 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: We give a comprehensive analysis of how scalar and tensor perturbations evolve in cosmologies with a smooth transition from power-law-like and de Sitter-like inflation to a radiation era. Analytic forms for the superhorizon and subhorizon perturbations in the inflationary and radiation dominated eras are found. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.532546
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  • 2
    Electronic Resource
    Electronic Resource
    Centrosymmetric lie algebras and boost-dilations (1996)
    Springer
    International journal of theoretical physics 35 (1996), S. 129-134 
    Details
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We define the Lie algebrac(n) of centrosymmetric matrices. It generates a noncompact and nonsemisimple local Lie group with the unusual property that expc(n) ⊂c(n). The group contains an invariant subgroup of Lorentz boost/ dilation transformations. Forn even, these form a subgroup of the conformal group of the Lorentzian metric with signature (− + − + ⋯ − +).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02082938
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  • 3
    Electronic Resource
    Electronic Resource
    Almost-homogeneity of the universe in higher-order gravity (1995)
    Springer
    General relativity and gravitation 27 (1995), S. 1309-1321 
    Details
    ISSN: 1572-9532
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the R+αR2 gravity theory, we show that if freely propagating massless particles have an almost isotropic distribution, then the spacetime is almost Friedmann-Robertson-Walker (frw). This extends the result proved recently in general relativity (α = 0), which is applicable to the microwave background after photon decoupling. The higher-order result is in principle applicable to a massless species that decouples in the early universe, such as a relic graviton background. Any future observations that show small anisotropies in such a background would imply that the geometry of the early universe were almostfrw.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02153319
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  • 4
    Electronic Resource
    Electronic Resource
    Quadrupole anisotropy from photon quantum effects (1996)
    Springer
    General relativity and gravitation 28 (1996), S. 239-248 
    Details
    ISSN: 1572-9532
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We consider quantum effects of an electromagnetic field in a radiation-dominated almostfrw spacetime. The dominant non-local quantum correction to the photon distribution is a quadrupole moment, corresponding to an effective anisotropic pressure in the energy-momentum tensor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02105426
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  • 5
    Electronic Resource
    Electronic Resource
    Backreaction Effects of Dissipation in Neutrino Decoupling (2000)
    Springer
    General relativity and gravitation 32 (2000), S. 1711-1725 
    Details
    ISSN: 1572-9532
    Keywords: Relativistic thermodynamics ; cosmology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Dissipative effects during neutrino decoupling in the early universe create a small backreaction on the Hubble rate, and lead to a small rise in temperature and entropy. We use a simplified thermo-hydrodynamic model, which provides a causal approximation to kinetic theory, in order to estimate the backreaction effects and the entropy production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001994404420
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  • 6
    Electronic Resource
    Electronic Resource
    Preface (2000)
    Springer
    General relativity and gravitation 32 (2000), S. 975-999 
    Details
    ISSN: 1572-9532
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001928124275
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  • 7
    Electronic Resource
    Electronic Resource
    Workshop 2: Cosmic Microwave Background, Lensing and Large-scale Structure (2000)
    Springer
    General relativity and gravitation 32 (2000), S. 1055-1058 
    Details
    ISSN: 1572-9532
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Papers presented in the second workshop are briefly reviewed. The 1+3 covariant approach to microwave background anisotropies and structure formation was well represented. Other topics included gravitational lensing and caustics, alternative approaches to galactic observations, conserved quantities in perturbation theory and primordial black holes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001969627001
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  • 8
    Electronic Resource
    Electronic Resource
    Exact Perturbations for Inflation with Smooth Exit (1998)
    Springer
    General relativity and gravitation 30 (1998), S. 289-297 
    Details
    ISSN: 1572-9532
    Keywords: COSMOLOGY ; INFLATION ; COSMOLOGICAL PERTURBATIONS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Toy models for the Hubble rate or the scalar field potential have been used to analyze the amplification of scalar perturbations through a smooth transition from inflation to the radiation era. We use a Hubble rate that arises consistently from a decaying vacuum cosmology, which evolves smoothly from nearly de Sitter inflation to radiation domination. We find exact solutions for super-horizon perturbations (scalar and tensor), and for sub-horizon perturbations in the vacuum- and radiation-dominated eras. The standard conserved quantity for super-horizon scalar perturbations is exactly constant for the growing modes, and zero for the decaying modes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018852929430
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  • 9
    Electronic Resource
    Electronic Resource
    Nonlinear Effects in the Cosmic Microwave Background (2000)
    Springer
    General relativity and gravitation 32 (2000), S. 1075-1090 
    Details
    ISSN: 1572-9532
    Keywords: Cosmology ; microwave background radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Major advances in the observation and theory of cosmic microwave background anisotropies have opened up a new era in cosmology. This has encouraged the hope that the fundamental parameters of cosmology will be determined to high accuracy in the near future. However, this optimism should not obscure the ongoing need for theoretical developments that go beyond the highly successful but simplified standard model. Such developments include improvements in observational modelling (e.g. foregrounds, non-Gaussian features), extensions and alternatives to the simplest inflationary paradigm (e.g. non-adiabatic effects, defects), and investigation of nonlinear effects. In addition to well known nonlinear effects such as the Rees–Sciama and Ostriker–Vishniac effects, further nonlinear effects have recently been identified. These include a Rees–Sciama-type tensor effect, time-delay effects of scalar and tensor lensing, nonlinear Thomson scattering effects and a nonlinear shear effect. Some of the nonlinear effects and their potential implications are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001973727910
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