FirstPeriodProjectB1 - TransRegio

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B1 - Early Dark Energy

Early Dark Energy might constitute an observable fraction of the total energy density of our Universe as far back as the time of matter radiation equality or even big bang nucleosynthesis. This is in sharp contrast to a cosmological constant or dark energy with a constant negative equation of state -- for those the fraction in dark energy, \Omega_h(z), is negligible at high redshift. Hence, a detection of Early Dark Energy would favor some form of dynamical dark energy over a cosmological constant.

Models predicting Early Dark Energy usually link the small present dark energy density to the huge age of our Universe. In such models the dark energy fraction \Omega_h(z) is only mildly varying with redshift at early times. One might thus hope to find a few percent of dark energy during structure formation and at recombination. A detection seems feasible, because Early Dark Energy alters the spectrum of CMB anisotropies and the growth of linear and nonlinear structures.

There are two major objectives of this project. One is to collect all available information contained in observations that are sensitive to the presence of early dark energy. We plan to limit or extract the behavior of \Omega_h(z) in particular for redshifts z\geq 2. A main tool for this will be the Cmbeasy code developed at Heidelberg and at Dartmouth college. The other main objective is to develop viable phenomenological quintessence models that can be used as an input for the tests of \Omega_h(z) in the observational projects concerning the time variation of Dark Energy. The whole project is conceived in close interaction with all projects in part B.
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