Model-independent dark energy reconstruction scheme using the geometrical form of the luminosity-distance relation

Abstract

We put forward a new model-independent reconstruction scheme for dark energy which utilizes the expected geometrical features of the luminosity-distance relation. The important advantage of this scheme is that it does not assume explicit ansatzes for cosmological parameters but only some very general cosmological properties via the geometrical features of the reconstructed luminosity-distance relation. Using the recently released supernovae data by the Supernova Legacy Survey together with a phase space representation, we show that the reconstructed luminosity-distance curves best fitting the data correspond to a slightly varying dark energy density with the Universe expanding slightly slower than the CDM model. However, the CDM model fits the data at 1 significance level and the fact that our best fitting luminosity-distance curve is lower than that of the corresponding CDM model could be due to systematics. The transition from an accelerating to a decelerating expansion occurs at a redshift larger than z 0:35. Interpreting the dark energy as a minimally coupled scalar field we also reconstruct the scalar field and its potential. We constrain m 0 using the baryon acoustic oscillation peak in the SDSS luminous red galaxy sample and find that the best fit is obtained with m 0 0:27, in agreement with the CMB data.

Backreaction: directions of progress

“…The data, however, does not exclude the possibility that the expansion could have already have gone from acceleration back to deceleration. There have been arguments that the observations would in fact slightly prefer deceleration today [43] and extra deceleration before acceleration [44], though such trends are not statistically significant in the present data. Another caveat is that the deceleration parameter is determined from distance observations, assuming that the relation between distance and expansion rate is the one given by the FRW metric.…”

Cosmological scaling solutions in generalised Gauss–Bonnet gravity theories

“…This possibility has been motivated by a wealth of high redshift observations, which indicate that the universe is presently undergoing a phase of accelerated expansion [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. (For a review, see, e.g.…”

“…In recent years, there has been considerable interest in the possibility that Einstein's theory of general relativity may become modified in high-curvature regimes and over large distance scales. This possibility has been motivated by a wealth of high redshift observations, which indicate that the universe is presently undergoing a phase of accelerated expansion [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]. (For a review, see, e.g.…”

The luminosity-redshift relation in brane-worlds: II. Confrontation with experimental data

“…Such a dark energy in general does not clump. A recent analysis [5] shows that a dark energy model with varying dark energy density going through a transition from an accelerating to a decelerating phase at redshift 0.45 fits well the observational data. Based on observations, the dark energy equation of state w = p/ρ is within about -1 ± 0.1 [6].…”