/ftp/cats/J_ApJ/677/1



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J/ApJ/677/1          Dimensionless coordinate distances            (Daly+, 2008)
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	table1.dat
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Beginning of ReadMe : J/ApJ/677/1 Dimensionless coordinate distances (Daly+, 2008) ================================================================================ Improved constraints on the acceleration history of the universe and the properties of the dark energy. Daly R.A., Djorgovski S.G., Freeman K.A., Mory M.P., O'Dea C.P., Kharb P., Baum S. <Astrophys. J., 677, 1-11 (2008)> =2008ApJ...677....1D ================================================================================ ADC_Keywords: Supernovae ; Redshifts ; Galaxies, radio Keywords: cosmological parameters - cosmology: observations cosmology: theory - dark matter - equation of state Abstract: We extend and apply a model-independent analysis method developed earlier by Daly & Djorgovski (2003ApJ...597....9D and 2004, Cat. J/ApJ/612/652) to new supernova, radio galaxy, and galaxy cluster samples to study the acceleration history of the universe and the properties of the dark energy. There is good agreement between results obtained with radio galaxies and supernovae, suggesting that both distance indicators are reliable. The deceleration parameter q(z) is obtained assuming only the validity of the FRW metric, allowing for a range of values of space curvature, and independent of a gravity theory and the physical nature of the contents of the universe. We show that q_0_ is independent of space curvature, and obtain q_0_=-0.48+/-0.11. The transition redshift when q_0_=0 is z_T_=0.78^+0.08^_-0.27_ for zero space curvature, and has a weak dependence on space curvature. We find good agreement between model-independent quantities and those predicted by general relativity, indicating that GR provides a good description of the data over look-back times of ten billion years.

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