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Improved constraints on the acceleration history of the Universe and the properties of the dark energy

Daly, Ruth A. and Djorgovski, S. G. and Freeman, Kenneth A. and Mory, Matthew P. and O'Dea, C. P. and Kharb, P. and Baum, S. (2008) Improved constraints on the acceleration history of the Universe and the properties of the dark energy. Astrophysical Journal, 677 (1). pp. 1-11. ISSN 0004-637X. doi:10.1086/528837.

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We extend and apply a model-independent analysis method developed earlier by Daly & Djorgovski 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 q0 = 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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Djorgovski, S. G.0000-0002-0603-3087
O'Dea, C. P.0000-0001-6421-054X
Kharb, P.0000-0003-3203-1613
Additional Information:© 2008 The American Astronomical Society. Received 2007 June 19; accepted 2007 December 17. We would like to thank the observers for their tireless efforts in obtaining the data used for this study. We would also like to thank the referee for very helpful comments and suggestions. This work was supported in part by US National Science Foundation grants AST-0507465 (R. A. D.) and AST-0407448 (S. G. D.), and the Ajax Foundation (S. G. D.).
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Ajax FoundationUNSPECIFIED
Subject Keywords:cosmological parameters; cosmology: observations; cosmology: theory; dark matter; equation of state
Issue or Number:1
Record Number:CaltechAUTHORS:DALapj08
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Official Citation:Improved Constraints on the Acceleration History of the Universe and the Properties of the Dark Energy Ruth A. Daly, S. G. Djorgovski, Kenneth A. Freeman, Matthew P. Mory, C. P. O'Dea, P. Kharb, and S. Baum 2008 ApJ 677 1-11 doi: 10.1086/528837
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13694
Deposited By: Tony Diaz
Deposited On:26 Aug 2009 23:59
Last Modified:08 Nov 2021 22:39

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