On the microwave background anisotropies produced by nonlinear voids

We derive a new class of exact solutions of Einstein's equations providing a physically plausible hydrodynamical description of cosmological matter in the radiative era, between nucleosynthesis and decoupling. The solutions are characterized by the Lemaître-Tolman-Bondi metric with a viscous fluid source, subjected to the following conditions: ͑a͒ the equilibrium state variables satisfy the equation of state of a mixture of an ultrarelativistic and a nonrelativistic ideal gases, where the internal energy of the latter has been neglected, ͑b͒ the particle numbers of the mixture components are independently conserved, ͑c͒ the viscous stress is consistent with the transport equation and entropy balance law of extended irreversible thermodynamics, with the coefficient of shear viscosity provided by kinetic theory. The satisfaction of ͑a͒, ͑b͒, and ͑c͒ restricts initial conditions in terms of an initial value function ⌬ i (s) , which in the limit of small density contrasts becomes the average of spatial gradients of the fluctuations of photon entropy per baryon in the initial hypersurface. For ⌬ i (s) 0 and choosing the phenomenological coefficients of the ''radiative gas'' model, we have an interactive photon-baryon mixture under local thermal equilibrium, with radiation dominance and temperatures characteristic of the radiative era (10 6 KϾTϾ10 3 K). Constraints on the observed anisotropy of the microwave cosmic radiation and the condition that decoupling occurs at TϭT D Ϸ4ϫ10 3 K yield an estimated value ͉⌬ i (s) ͉Ϸ10 Ϫ8 which can be associated with a bound on promordial entropy fluctuations. The Jeans mass at decoupling is of the same order of magnitude as that of baryon dominated perturbation models (Ϸ10 16 M ᭪ ).

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“…In order to provide an interpretation for (38), we remark (from (17), (19) and (28)) that the entropy per photon along the initial hypersurface…”

Section: Initial Conditions and Exact Initial Perturbationsmentioning

confidence: 99%

Exact inhomogeneous cosmologies whose source is a radiation-matter mixture with consistent thermodynamics

Sussman

Pavón

1999

Phys. Rev. D

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“…The main references are Occhionero et al (1978Occhionero et al ( , 1981Occhionero et al ( and 1983, Maeda et al (1983), Sato et al (1982Sato et al ( , 1983Sato et al ( and 1984, Suto et al (1984), with later contributions by Lake and Pim (1985), Pim and Lake (1986 and 1988), Bonnor andChamorro (1990 and and Chamorro (1991).…”

Section: Evolution Of Voidsmentioning

confidence: 99%

“…The creation and evolution of a black hole can be studied (Barnes 1970). In the Schwarzschild and Kerr solutions, the black hole is stationary and present in unchanged form throughout the whole history of the spacetime.…”

Section: Other Propertiesmentioning

confidence: 99%

Physics and cosmology in an inhomogeneous Universe

Krasiński

1997

Inhomogeneous Cosmological Models

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Examples are presented of applications of the Lemaître -Tolman model to problems of astrophysics and gravitation theory. They are: 1. Inferring the spatial distribution of matter by interpretation of observations; 2. Interaction of inhomogeneities in matter distribution with the CMB radiation; 3. Evolution of voids; 4. Singularities; 5. Influence of electromagnetic field on gravitational collapse. This review is meant to demonstrate that the theory is already well-prepared to meet the challenges posed by an inhomogeneous Universe. Why consider inhomogeneous models?The more appropriate question here is: why not? We know that the FriedmannLemaître -Robertson -Walker (FLRW) models are a realistic first approximation to the geometry and physics of our Universe. We know (from many published examples, and see also below) that their generalizations are still reasonably simple. The urge to explore the unknown (once upon a time considered a necessary part of a scientist's personality) still lingers in the physics community. This should be a sufficient motivation for the beginning; more of it will appear along the way.In this article, only one class of models will be discussed, the Lemaître (1933) -Tolman (1934 (LT) models, and only a small selection of existing material will be presented. For a more complete treatment see the other review by this author (Krasiński 1997). The Lemaître -Tolman modelAssume that the Universe is isotropic around one observer, but not spatially homogeneous. (How to save the "cosmological principle" in such a model will be explained the end of this section.) Assume that the matter of the Universe is dust. In comoving coordinates, the metric form is then:The case R, r = 0 has to be considered separately and it leads to the solution found by Datt (1938, see also Krasiński 1997. It is an inhomogeneous generalization of the KantowskiSachs (1966) solution and has interesting geometrical properties, but has not been exploited 1

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“…The effects of primordial voids on the CMB have been investigated by a number of authors (Thompson & Vishniac 1987; Sato 1985; Martínez‐González, Sanz & Silk 1990; Martínez‐González & Sanz 1990; Liddle & Wands 1992; Panek 1992; Arnau et al 1993; Mészáros 1994; Fullana, Arnau & Saez 1996; Mészáros & Molnár 1996; Shi, Widrow & Dursi 1996; Baccigalupi, Amendola & Occhionero 1997; Amendola, Baccigalupi & Occhionero 1998; Baccigalupi 1998). The most complete investigation was carried out by Sakai, Sugiyama & Yokoyama (1999) who modelled the effect for a distribution of equally sized voids.…”

Section: Introductionmentioning

confidence: 99%

A possible contribution to CMB anisotropies at high from primordial voids

Griffiths¹,

Kunz²,

Silk³

2003

Monthly Notices of the Royal Astronomical Society

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We present preliminary results of an analysis into the effects of primordial voids on the cosmic microwave background (CMB). We show that an inflationary bubble model of void formation predicts excess power in the CMB angular power spectrum that peaks between 2000 < ℓ < 3000. Therefore, voids that exist on or close to the last scattering surface at the epoch of decoupling can contribute significantly to the apparent rise in power on these scales recently detected by the Cosmic Background Imager (CBI).

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On the microwave background anisotropies produced by nonlinear voids

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Exact inhomogeneous cosmologies whose source is a radiation-matter mixture with consistent thermodynamics

Exact inhomogeneous cosmologies whose source is a radiation-matter mixture with consistent thermodynamics

Physics and cosmology in an inhomogeneous Universe

A possible contribution to CMB anisotropies at high from primordial voids

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