All Figures

$\begin{figure} \par\hspace*{-2mm}\includegraphics[width=7.3cm,clip]{5067fig1.ps}\vspace*{5mm} \includegraphics[width=7.5cm,clip]{5067fig2.ps}\end{figure}$ Figure 1: Contour constraints on the transition at epoch $a_{\rm t}= 1 / (1 + z_{\rm t})$ , and the rate of the transition $\Gamma$ . The results are independent of $\Gamma$ when it is sufficiently large. Bottom figure shows the results in the ( $\Omega _{ \rm Q}$ , $a_{\rm t}$ ) plane.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{5067fig3.eps}\vspace*{5mm} \includegraphics[width=7.5cm,clip]{5067fig4.eps}\end{figure}$ Figure 2: a) Residual Hubble diagram with respect to an empty universe for models with a transition at epoch $a_{\rm t}= 1/(1+z_{\rm t}) = 0.0$ , 0.3, 0.6, 0.7 and 0.8 compared with a binned version of the SNIa compilation of Davis et al. (2007). Note that as explained in the text low values of $a_{\rm t}$ all give similar curves as the $\Lambda$ CDM model. b) Same quantity for models with a transition at epoch $a_{\rm t}= 0.565$ and $w_{\rm i}= 0, -0.2, -0.4, -0.6$ .
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5067fig5.ps}\end{figure}$ Figure 3: Angular power spectrum of CMB fluctuations for models presenting a transition at epoch $a_{\rm t}= 1 / (1 + z_{\rm t}) = 0$ , 0.3, 0.6, 0.7 and 0.8 (all other parameters fixed) compared with the WMAP 3 TT spectrum. Apart from the large scale (low $\ell$ ) power, the only difference between the spectra is a shift in the spectrum as a result of the modification of the angular distance to the last scattering surface.
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{5067fig6.ps}\vspace*{5mm} \includegraphics[width=7.5cm,clip]{5067fig7.ps}\end{figure}$ Figure 4: Contour constraints on the transition epoch $a_{\rm t}/ a_0 = 1 / (1 + z_{\rm t})$ versus the value of the dark energy density parameter at present time, $\Omega _{ \rm Q}$ from the CMB alone ( upper) using WMAP3, CBI, VSA and Boomerang data. Constraints on the same quantities when combined with supernovae data ( lower).
Open with DEXTER

In the text

$\begin{figure} \par\includegraphics[width=7.4cm,clip]{5067fig8.eps}\vspace*{5mm} \includegraphics[width=7.4cm,clip]{5067fig9.eps}\end{figure}$ Figure 5: Comparison of $\Omega _{\rm m}-\Omega _\Lambda$ fit for the two models discussed in Sect. 4 for an observer at z = 0 (after the transition in the quintessence model) and z = 0.3(during the transition). At z = 0.3 the two models are very easily distinguished as one of them corresponds to a pure matter model, whereas one corresponds to a cosmological constant model with $\Omega _\Lambda = 0.5$ . On the contrary, at z = 0 both models look like a cosmological constant model, and cannot be distinguished at the 2 $\sigma$ level.
Open with DEXTER

In the text

$\begin{figure} \par\hspace{-2mm}\includegraphics[width=7.3cm,clip]{5067fig1.ps}\vspace{5mm} \includegraphics[width=7.5cm,clip]{5067fig2.ps}\end{figure}$	Figure 1: Contour constraints on the transition at epoch $a_{\rm t}= 1 / (1 + z_{\rm t})$ , and the rate of the transition $\Gamma$ . The results are independent of $\Gamma$ when it is sufficiently large. Bottom figure shows the results in the ( $\Omega _{ \rm Q}$ , $a_{\rm t}$ ) plane.
Open with DEXTER

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{5067fig6.ps}\vspace*{5mm} \includegraphics[width=7.5cm,clip]{5067fig7.ps}\end{figure}$	Figure 4: Contour constraints on the transition epoch $a_{\rm t}/ a_0 = 1 / (1 + z_{\rm t})$ versus the value of the dark energy density parameter at present time, $\Omega _{ \rm Q}$ from the CMB alone ( upper) using WMAP3, CBI, VSA and Boomerang data. Constraints on the same quantities when combined with supernovae data ( lower).
Open with DEXTER