Causal compensated perturbations in cosmology

Veeraraghavan, S.; Stebbins, Albert

doi:10.1086/169457

Cited by 95 publications

(153 citation statements)

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“…If the seeds do not interact directly with other types of matter, the conservation equations (14) and (15) imply that the metric perturbations only a ect the seed perturbations at second order since bare s and p s terms may be dropped. They become [29] It is useful to subdivide the stress-free class of scalar perturbations from the general possibilities. A \stress-free" perturbation has dimensionless stresses (S,S ) that are much smaller than the comoving curvature perturbation .…”

Section: B Seed Stressmentioning

confidence: 99%

Structure of structure formation theories

1999

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We study the general structure of models for structure formation, with applications to the reverse engineering of the model from observations. Through a careful accounting of the degrees of freedom in covariant gravitational instability theory, w e show that the evolution of structure is completely speci ed by the stress history of the dark sector. The study of smooth, entropic, sonic, scalar anisotropic, vector anisotropic, and tensor anisotropic stresses reveals the origin, robustness, and uniqueness of speci c model phenomenology. We construct useful and illustrative analytic solutions that cover cases with multiple species of di ering equations of state relevant to the current generation of models, especially those with e ectively smooth components. We present a simple case study of models with phenomenologies similar to that of a CDM model to highlight reverse-engineering issues. A critical-density universe dominated by a single type of dark matter with the appropriate stress history can mimic a CDM model exactly.

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Section: B Seed Stressmentioning

confidence: 99%

Structure of structure formation theories

1999

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“…Here X = |x − x | and the upper index 'S' indicates that these are the 'subsequent' fluctuations, according to the notation of Veeraraghavan & Stebbins [29], to be distinguished from the 'initial' fluctuations. We are mostly interested in computing the inhomogeneities at late times in the matter era.…”

Section: Cosmological Consequencesmentioning

confidence: 99%

Primordial Adiabatic Fluctuations from Cosmic Defects

Avelino

Martins²

2000

Phys. Rev. Lett.

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We point out that in the context of "two-metric" theories of gravity there is the possibility that cosmic defects will produce a spectrum of primordial adiabatic density perturbations. This will happen when the speed characterising the defect-producing scalar field is much larger than the speed characterising gravity and all standard model particles. This model will exactly mimic the standard predictions of inflationary models, with the exception of a small non-Gaussian signal which could be detected by future experiments. We briefly discuss defect evolution in these scenarios and analyze their cosmological consequences. PACS number(s): 98.80. Cq, 11.27.+d, 98.70.Vc, 98.65.Dx

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“…We suppose that it is a small perturbation which does not contribute to the background (this is the so-called "stiff approximation" (see e.g. [8])). We decompose its scalar components as :…”

Section: Scalar Perturbationsmentioning

confidence: 99%

“…[8][9] [26][27]). To understand better their role we shall restrict our attention to scalar perturbations and shall rewrite them, in the context here considered of a radiation dominated universe, as (see (4) (9) (10-11) (13))…”

Section: "Integral Constraints" and Compensationmentioning

confidence: 99%

See 1 more Smart Citation

Erratum: Cosmological perturbations seeded by topological defects: Setting the initial conditions [Phys. Rev. D 56, 7608 (1997)]

Deruelle¹,

Langlois²,

Uzan³

1998

Phys. Rev. D

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We consider a perfectly homogeneous and isotropic universe which undergoes a sudden phase transition. If the transition produces topological defects, which we assume, perturbations in the geometry and the cosmic fluid also suddenly appear. We apply the standard general relativistic junction conditions to match the pre-and post-transition eras and thus set the initial conditions for the perturbations. We solve their evolution equations analytically in the case when the defects act as a coherent source and their density scales like the background density. We show that isocurvature as well as adiabatic perturbations are created, in a ratio which is independent of the detailed properties of the defects. We compare our result to the initial conditions currently used in the literature and show how the cosmic fluid naturally "compensates" for the presence of the defects.1

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Causal compensated perturbations in cosmology

Cited by 95 publications

References 0 publications

Structure of structure formation theories

Structure of structure formation theories

Primordial Adiabatic Fluctuations from Cosmic Defects

Erratum: Cosmological perturbations seeded by topological defects: Setting the initial conditions [Phys. Rev. D 56, 7608 (1997)]

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