Curvature and isocurvature perturbations in a three-fluid model of curvaton decay

Gupta, S.; Malik, Karim A.; Wands, David

doi:10.1103/physrevd.69.063513

Cited by 51 publications

(112 citation statements)

References 38 publications

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“…In the standard inflation models the scalar field responsible for the accelerated expansion of the universe, the inflaton, also provides these fluctuations [2]. Recently a related but different scenario has become become popular: the curvaton paradigm [3,4,5,6,7,8,9,10,11,12]. Here the fluctuations are not generated by the inflaton, but by a different scalar field, the curvaton.…”

Section: Introductionmentioning

confidence: 99%

A numerical study of non-Gaussianity in the curvaton scenario

Malik¹,

Lyth²

2006

J. Cosmol. Astropart. Phys.

126

121

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We study the curvaton scenario using gauge-invariant second order perturbation theory and solving the governing equations numerically. Focusing on large scales we calculate the non-linearity parameter fNL in the two-fluid curvaton model and compare our results with previous analytical studies employing the sudden decay approximation. We find good agreement of the two approaches for large curvaton energy densities at curvaton decay, Ω σdec , but significant differences of up to 10% for small Ω σdec .

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Section: Introductionmentioning

confidence: 99%

A numerical study of non-Gaussianity in the curvaton scenario

Malik¹,

Lyth²

2006

J. Cosmol. Astropart. Phys.

126

121

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“…In practice the curvaton energy density is continually decaying once the curvaton begins oscillating until finally (when Γ > H) its density becomes negligible, and during this decay process ζ χ does not remain constant [31,32].…”

Section: Numerical Calculationmentioning

confidence: 99%

“…In fact a more careful treatment of the continuous decay of the curvaton [31,32] shows that the transfer coefficient at first order, r in Eq. (37), is a function solely of the parameter…”

Section: Numerical Calculationmentioning

confidence: 99%

Non-Gaussianity of the primordial perturbation in the curvaton model

2006

Self Cite

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We use the δN -formalism to investigate the non-Gaussianity of the primordial curvature perturbation in the curvaton scenario for the origin of structure. We numerically calculate the full probability distribution function allowing for the non-instantaneous decay of the curvaton and compare this with analytic results derived in the sudden-decay approximation. We also present results for the leading-order contribution to the primordial bispectrum and trispectrum. In the suddendecay approximation we derive a fully non-linear expression relating the primordial perturbation to the initial curvaton perturbation. As an example of how non-Gaussianity provides additional constraints on model parameters, we show how the primordial bispectrum on CMB scales can be used to constrain variance on much smaller scales in the curvaton field. Our analytical and numerical results allow for multiple tests of primordial non-Gaussianity, and thus they can offer consistency tests of the curvaton scenario.

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“…In order to evaluate the final curvature perturbation in dark matter, it is convenient to construct a compound fluid that comprises the dark matter and a fraction B χ ≡ Γ σχ /Γ σ of the curvaton fluid such that the source term coming from curvaton decay vanishes in its equation of energy conservation [13]:…”

Section: Fig 1: Comparison Of Numerical (Red Solid Line) and Analytimentioning

confidence: 99%

“…Ref. [13], building on the general formalism developed in [14], has considered a three-fluid model of curvaton decay, albeit assuming that dark matter fully originates in the decay of the curvaton. Finally, Ref.…”

Section: Introductionmentioning

confidence: 99%

Neutralino dark matter and the curvaton

Lemoine

Martin

2007

Phys. Rev. D

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We build a realistic model of curvaton cosmology, in which the energy content is described by radiation, WIMP dark matter and a curvaton component. We calculate the curvature and isocurvature perturbations, allowing for arbitrary initial density perturbations in all fluids, following all species and their perturbations from the onset of dark matter freeze-out onto well after curvaton decay. We provide detailed numerical evaluations as well as analytical formulae which agree well with the latter. We find that substantial isocurvature perturbations, as measured relatively to the total curvature perturbation, can be produced even if the curvaton energy density is well underdominant when it decays; high precision measurements of cosmic microwave background anisotropies may thus open a window on underdominant decoupled species in the pre-nucleosynthesis early Universe. We also find that in a large part of parameter space, curvaton decay produces enough dark matter particles to restore WIMP annihilations, leading to the partial erasure of any pre-existing dark matter -radiation isocurvature perturbation.

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Curvature and isocurvature perturbations in a three-fluid model of curvaton decay

Cited by 51 publications

References 38 publications

A numerical study of non-Gaussianity in the curvaton scenario

A numerical study of non-Gaussianity in the curvaton scenario

Non-Gaussianity of the primordial perturbation in the curvaton model

Neutralino dark matter and the curvaton

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