Showing papers by "Camille Bonvin published in 2006"
TL;DR: In this article, the authors derived an expression for the luminosity distance in a perturbed Friedmann universe and derived the correlation function and the power spectrum of the LDM fluctuations and expressed them in terms of the initial spectrum of a Bardeen potential.
Abstract: We derive an expression for the luminosity distance in a perturbed Friedmann universe. We define the correlation function and the power spectrum of the luminosity distance fluctuations and express them in terms of the initial spectrum of the Bardeen potential. We present semianalytical results for the case of a pure CDM (cold dark matter) universe. We argue that the luminosity distance power spectrum represents a new observational tool which can be used to determine cosmological parameters. In addition, our results shed some light into the debate whether second order small scale fluctuations can mimic an accelerating universe.
262 citations
TL;DR: It is demonstrated that if k-essence can solve the coincidence problem and play the role of dark energy in the Universe, the fluctuations of the field have to propagate superluminally at some stage, and it is argued that this implies that successful k-Essence models violate causality.
Abstract: We demonstrate that if k-essence can solve the coincidence problem and play the role of dark energy in the Universe, the fluctuations of the field have to propagate superluminally at some stage. We argue that this implies that successful k-essence models violate causality. It is not possible to define a time ordered succession of events in a Lorentz invariant way. Therefore, k-essence cannot arise as a low energy effective field theory of a causal, consistent high energy theory.
135 citations
TL;DR: It is shown that the dipole of the luminosity distance is a useful observational tool which allows us to determine the Hubble parameter as a function of redshift H(z) and to distinguish between different models for dark energy.
Abstract: We show that the dipole of the luminosity distance is a useful observational tool which allows us to determine the Hubble parameter as a function of redshift H(z). We determine the number of supernovae needed to achieve a given precision for H(z) and to distinguish between different models for dark energy. We analyze a sample of nearby supernovae and find a dipole consistent with the cosmic microwave background at a significance of more than 2sigma.
117 citations