DEFROST: a new code for simulating preheating after inflation

At the end of inflation, dynamical instability can rapidly deposit the energy of homogeneous cold inflaton into excitations of other fields. This process, known as preheating, is rather violent, inhomogeneous and non-linear, and has to be studied numerically. This paper presents a new code for simul...

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Bibliographic Details
Published in:Journal of cosmology and astroparticle physics 2008-11, Vol.2008 (11), p.009
Main Author: Frolov, Andrei V
Format: Article
Language:English
Subjects:
ACCURACY
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CHAOS THEORY
DISTRIBUTION
DISTRIBUTION FUNCTIONS
ENERGY DENSITY
EXCITATION
GALACTIC EVOLUTION
INFLATIONARY UNIVERSE
NONLINEAR PROBLEMS
SCALAR FIELDS
TURBULENCE
UNIVERSE
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Summary:At the end of inflation, dynamical instability can rapidly deposit the energy of homogeneous cold inflaton into excitations of other fields. This process, known as preheating, is rather violent, inhomogeneous and non-linear, and has to be studied numerically. This paper presents a new code for simulating scalar field dynamics in an expanding universe written for that purpose. Compared to available alternatives, it significantly improves both the speed and the accuracy of calculations, and is fully instrumented for 3D visualization. We reproduce previously published results on preheating in simple chaotic inflation models, and further investigate non-linear dynamics of the inflaton decay. Surprisingly, we find that the fields do not 'want' to thermalize in quite the way that one would think. Instead of directly reaching equilibrium, the evolution appears to be stuck in a rather simple but quite inhomogeneous state. In particular, a one-point distribution function of total energy density appears to be universal among various two-field preheating models, and is exceedingly well described by a log-normal distribution. It is tempting to attribute this state to scalar field turbulence.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2008/11/009