Response of distance measures to the equation of state

Saini, Tarun Deep ; Padmanabhan, T. ; Bridle, Sarah (2003) Response of distance measures to the equation of state Monthly Notices of the Royal Astronomical Society, 343 (2). pp. 533-538. ISSN 0035-8711

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Official URL: http://onlinelibrary.wiley.com/doi/10.1046/j.1365-...

Related URL: http://dx.doi.org/10.1046/j.1365-8711.2003.06685.x

Abstract

We show that the distance measures (such as the luminosity and angular diameter distances) are linear functionals of the equation of state function w(z) of the dark energy to a fair degree of accuracy in the regimes of interest. That is, the distance measures can be expressed as a sum of (i) a constant and (ii) an integral of a weighting function multiplied by the equation of state parameter w(z). The existence of such an accurate linear response approximation has several important implications. (1) Fitting a constant-w model to the data drawn from an evolving model has a simple interpretation as a weighted average of w(z). (2) Any polynomial (or other expansion coefficients) can also be expressed as weighted sums of the true w. (3) A replacement for the commonly used heuristic equation for the effective w, as determined by the cosmic microwave background, can be derived and the result is found to be quite close to the heuristic expression commonly used. (4) The reconstruction of w(z) by Huterer & Starkman can be expressed as a matrix inversion. In each case the limitations of the linear response approximation are explored and found to be surprisingly small.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Methods: Statistical; Cosmological Parameters; Cosmology: Theory
ID Code:73542
Deposited On:06 Dec 2011 09:00
Last Modified:06 Dec 2011 09:00

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