AAS 207th Meeting, 8-12 January 2006
Session 152 Cosmology, Early Universe, Cosmic Distance Scale II
Oral, Wednesday, 10:00-11:30am, January 11, 2006, Balcony A

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[152.02] Uncovering the Acceleration History of the Universe and the Secrets of the Dark Energy

R. A. Daly (Penn State University), S. G. Djorgovski (California Institute of Technology)

Type Ia supernovae observations allow direct, model-independent determinations of the dimensionless expansion [E(z)] and acceleration [q(z)] rates of the universe as functions of redshift. The only assumptions required to obtain E(z) and q(z) from luminosity distances are that the universe is homogeneous and isotropic on large scales, and is spatially flat. Thus, E(z) and q(z) are obtained without specifying a gravity theory, or nature or properties of the dark energy. The values of E(z) and q(z) may then be combined to solve for the pressure, energy density, equation of state, potential energy density, and kinetic energy density of the dark energy as functions of redshift by specifying a theory of gravity.

Results obtained with a sample of 268 type Ia supernovae will be presented and compared with expectations in the LCDM model.

The author(s) of this abstract have provided an email address for comments about the abstract: rdaly@psu.edu

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