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Долгов, Н. А.

doi:10.1023/a:1015362426688

Cited by 2 publications

(2 citation statements)

References 7 publications

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“…A period of turbulence in the primordial universe can leave an observable trace today in the form of a stochastic background of gravitational waves. The most natural source of turbulence in the early universe is a first order phase transition (see [13] for another potential source of turbulence), where bubbles of the broken phase nucleate and expand into the symmetric phase. Therefore we concentrate on this case.…”

Section: Gravitational Waves From Turbulencementioning

confidence: 99%

Gravitational waves from stochastic relativistic sources: Primordial turbulence and magnetic fields

2006

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The power spectrum of a homogeneous and isotropic stochastic variable, characterised by a finite correlation length, does in general not vanish on scales larger than the correlation scale. If the variable is a divergence free vector field, we demonstrate that its power spectrum is blue on large scales. Accounting for this fact, we compute the gravitational waves induced by an incompressible turbulent fluid and by a causal magnetic field present in the early universe. The gravitational wave power spectra show common features: they are both blue on large scales, and peak at the correlation scale. However, the magnetic field can be treated as a coherent source and it is active for a long time. This results in a very effective conversion of magnetic energy in gravitational wave energy on super-horizon scales. Turbulence instead acts as a source for gravitational waves over a time interval much shorter than a Hubble time, and the conversion on super-horizon scales is much less effective. We also derive a strong constraint on the amplitude of a primordial magnetic field when the correlation length is much smaller than the horizon.

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Section: Gravitational Waves From Turbulencementioning

confidence: 99%

Gravitational waves from stochastic relativistic sources: Primordial turbulence and magnetic fields

2006

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“…They are, for example, the sterile neutrinos, majorons and even shadow particles. Detailed review of possible candidates can be found in Sommer-Larsen & Dolgov (2001) and Dolgov (2002). However, our estimates use the spectral moments and therefore do not forbid the existence of multicomponent heavy DM particles with both thermal and non-thermal (Lin et al 2001) distributions with the same spectral moments m−2 and m0.…”

Section: Characteristics Of the Initial Power Spectrummentioning

confidence: 99%

Statistical characteristics of the observed Ly α forest and the shape of initial power spectrum

Demiański¹,

Doroshkevich²,

Turchaninov³

2003

Monthly Notices of the Royal Astronomical Society

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Properties of approximately 4500 observed Ly α absorbers are investigated using the model of formation and evolution of dark matter (DM) structure elements based on the modified Zel'dovich theory. This model is generally consistent with simulations of absorber formation, describes the large‐scale structure (LSS) observed in the galaxy distribution at small redshifts reasonably well and emphasizes the generic similarity of the LSS and absorbers. The simple physical model of absorbers asserts that they are composed of DM and gaseous matter. It allows us to estimate the column density and overdensity of DM and gaseous components and the entropy of the gas trapped within the DM potential wells. The parameters of the DM component are found to be consistent with theoretical expectations for the Gaussian initial perturbations with the warm dark matter‐like power spectrum. The basic physical factors responsible for the evolution of the absorbers are discussed. The analysis of redshift distribution of absorbers confirms the self‐consistency of the adopted physical model, Gaussianity of the initial perturbations and allows one to estimate the shape of the initial power spectrum at small scales that, in turn, restricts the mass of the dominant fraction of DM particles to MDM≥ 1.5–5 keV. Our results indicate a possible redshift variations of intensity of the ultraviolet background by approximately a factor of 2–3 at redshifts z∼ 2–3.

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Untitled

Cited by 2 publications

References 7 publications

Gravitational waves from stochastic relativistic sources: Primordial turbulence and magnetic fields

Gravitational waves from stochastic relativistic sources: Primordial turbulence and magnetic fields

Statistical characteristics of the observed Ly α forest and the shape of initial power spectrum

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