HEP/Astro Seminar, Wednesday 7th October 1998

Tracking Behavior in Quintessence Cosmology

Limin Wang (Columbia)

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Abstract

Recent cosmological observations suggest that a large fraction
of the energy density of the universe has negative pressure.   
Quintessence, a slowly-varying, spatially inhomogeneous component, 
such as a scalar field evolving down a potential have been considered 
as a candidate for the ``missing energy''.  The energy density of 
quintessence and matter density decrease at different rates as the 
universe expands. Hence, it seems that the initial condition has to be 
tremendously fine tuned to make two of them comparable today. We find 
that for a broad family of quintessence models, the cosmology is actually 
extremely insensitive to the initial conditions.  The scalar field 
``tracks'' a solution purely determined by the form of the potential.
We also present the general conditions a model has to satisfy so that
it exhibits this kind of ``tracking behavior''.

3:30pm, Smith Lab 4079