Cosmological Perturbations From Inhomogeneous Reheating, Freeze-Out, and Mass Domination

By G. Dvali, A. Gruzinov, M. Zaldarriaga. 2003

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We generalize a recently proposed mechanism for the origin of primordial metric perturbations in inflationary models. Quantum fluctuations of light scalar fields during inflation gives rise to superhorizon fluctuations of masses and reaction rates of various particles. Reheating, freeze-out, and matter-domination processes become inhomogeneous and generate superhorizon metric perturbations. We also calculate the degree of non-Gaussianity ${f}_{\mathrm{nl}}$ for this new model of cosmological perturbations. The precise value of ${f}_{\mathrm{nl}}$ depends on the specific models, but $|{f}_{\mathrm{nl}}|\ensuremath{\sim}\mathrm{few}$ is a natural lower bound for our mechanisms. This is much larger than the currently assumed theoretical value ${f}_{\mathrm{nl}}\ensuremath{\sim}\mathrm{tilt}\ensuremath{\lesssim}0.05,$ and is thought to be observable. In a particularly attractive model of inhomogeneous mass domination, the non-Gaussianity of perturbations generated by our mechanism is simply ${f}_{\mathrm{nl}}=5,$ irrespective of the detailed structure of the underlying field theory.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/bdb62f5fb170cca867a5d241d3071d283a3da896

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Citations in the corpus

Inflation and String Theory (2014, background): “A more dramatic example of the effect of multiple fields arises if the inflaton contribution to the scalar perturbations is negligible in comparison to the perturbations arising from a curvaton [131], or through modulated reheating [172, 256].”
Planck 2015 results. XVII. Constraints on primordial non-Gaussianity (2015, unknown): “…2009) or from fluctuations in the inflaton decay rate or interactions, as found in modulated (p)reheating and modulated hybrid inflation (Kofman 2003; Dvali et al. 2004a,b; Bernardeau et al. 2004; Zaldarriaga 2004; Lyth 2005; Salem 2005; Lyth & Riotto 2006; Kolb et al. 2006; Cicoli et al. 2012).”
The shape of non-Gaussianities (2004, background): “Examples of this general scenario are the curvaton models [8], models with fluctuations in the reheating efficiency [9, 10] and multi-field inflationary models [17] (4).”
Primordial non-Gaussianity from the large-scale structure (2010, background): “Generation of a large non-Gaussian signal is also expected at reheating [22] and in the ekpyrotic scenario [23].”
SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: COSMOLOGICAL INTERPRETATION (2010, background): “…“curvaton” scenarios (Linde & Mukhanov 1997; Lyth et al. 2003); multi-field models in which one field modulates the decay rate of inflaton field (Dvali et al. 2004a,b; Zaldarriaga 2004); multi-field models in which a violent production of particles and non-linear reheating, called…”
Planck 2018 results. IX. Constraints on primordial non-Gaussianity (2019, unknown): “…in the decay rate or interactions of the inflaton field, as realized in modulated (p)reheating and modulated hybrid inflationary models (Kofman 2003; Dvali et al. 2004a,b; Bernardeau et al. 2004; Zaldarriaga 2004; Lyth 2005; Salem 2005; Lyth & Riotto 2006; Kolb et al. 2006; Cicoli et al. 2012).”
Review of local non-Gaussianity from multi-field inflation (2010, background): “In a similar way, the mass of the decaying particle may be modulated [73].”
FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: COSMOLOGICAL INTERPRETATION (2008, unknown): “For example, a multi-field model known as the curvaton scenario can result in much larger values of f localNL (Linde & Mukhanov 1997; Lyth et al. 2003), so can the models with field-dependent (variable) decay widths for reheating of the universe after inflation (Dvali et al. 2004b,a).”