A kinematical approach to dark energy studies

By David Rapetti, S. Allen, M. Amin, R. Blandford. 2006

259 citations recorded by the source corpus.

We present and employ a new kinematical approach to cosmological 'dark energy' studies. We construct models in terms of the dimensionless second and third derivatives of the scalefactor a(t) with respect to cosmic time t, namely the present-day value of the deceleration parameter q0 and the cosmic jerk parameter, j(t). An elegant feature of this parametrization is that all � cold dark matter (� CDM) models have j(t) = 1 (constant), which facilitates simple tests for departures from theCDM paradigm. Applying our model to the three best available sets of redshift-independent distance measurements, from Type Ia supernova and X-ray cluster gas mass fraction measurements, we obtain clear statistical evidence for a late-time transition from a decelerating to an accelerating phase. For a flat model with constant jerk, j(t) = j, we measure q0 =− 0.81 ± 0.14 and j = 2.16 +0.81 −0.75 , results that are consistent withCDM at about the 1σ confidence level. A standard 'dynamical' analysis of the same data, employing the Friedmann equations and modelling the dark energy as a fluid with an equation-of-state parameter, w (constant), givesm = 0.306 +0.042 −0.040 and w =− 1.15 +0.14 −0.18, also consistent with � CDM at about the 1σ level. In comparison to dynamical analyses, the kinematical approach uses a different model set and employs a minimum of prior information, being independent of any particular gravity theory. The results obtained with this new approach therefore provide important additional information and we argue that both kinematical and dynamical techniques should be employed in future dark energy studies, where possible. Our results provide further interesting support for the concordanceCDM paradigm.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/9c446494bb7ab1177a3b00bce8469459e8e4f2a1

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Citations in the corpus

New constraints on dark energy from the observed growth of the most X-ray luminous galaxy clusters (2007, methodology): “Cosmological constraints were determined via Markov 3 http://lambda.gsfc.nasa.gov Chain Monte Carlo, employing the Metropolis algorithm; the calculations were performed using a modified version of the COSMOMC code4 of Lewis & Bridle (2002, see also Rapetti et al. 2005, 2007).”
Improved constraints on dark energy from Chandra X-ray observations of the largest relaxed galaxy clusters (2007, methodology): “…combining the two techniques but using larger target samples, should open the possibility for precise distance-redshift measurements and good control of systematic uncertainties, employing both kinematic and dynamical analyses (e.g. Rapetti et al. 2007; Riess et al. 2007 and references therein).”
The WiggleZ Dark Energy Survey: joint measurements of the expansion and growth history at z < 1 (2012, methodology): “Finally, we fitted our dataset with a “kinematical” cosmological model (Rapetti et al. 2007) which is parameterized in terms of the dimensionless second and third derivatives c© 0000 RAS, MNRAS 000, 000–000 of the scale factor a(t) with respect to time, the deceleration parameter q(t) = −H−2(ä/a)…”