A test of the nature of cosmic acceleration using galaxy redshift distortions
Abstract
Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the equations of cosmic expansion, accounting for about 75 per cent of the total energy density in the Universe. The simplest option for this "dark energy" corresponds to a cosmological constant, perhaps related to the quantum vacuum energy. Physically viable alternatives invoke either the presence of a scalar field with an evolving equation of state, or extensions of general relativity involving higher-order curvature terms or extra dimensions. Although they produce similar expansion rates, different models predict measurable differences in the growth rate of large-scale structure with cosmic time. A fingerprint of this growth is provided by coherent galaxy motions, which introduce a radial anisotropy in the clustering pattern reconstructed by galaxy redshift surveys. Here we report a measurement of this effect at a redshift of 0.8. Using a new survey of more than 10,000 faint galaxies, we measure the anisotropy parameter b = 0.70 +/- 0.26, which corresponds to a growth rate of structure at that time of f = 0.91 +/- 0.36. This is consistent with the standard cosmological-constant model with low matter density and flat geometry, although the error bars are still too large to distinguish among alternative origins for the accelerated expansion. This could be achieved with a further factor-of-ten increase in the sampled volume at similar redshift.
Keywords
Cite
@article{arxiv.0802.1944,
title = {A test of the nature of cosmic acceleration using galaxy redshift distortions},
author = {L. Guzzo and M. Pierleoni and B. Meneux and E. Branchini and O. Le Fevre and C. Marinoni and B. Garilli and J. Blaizot and G. De Lucia and A. Pollo and H. J. McCracken and D. Bottini and V. Le Brun and D. Maccagni and J. P. Picat and R. Scaramella and M. Scodeggio and L. Tresse and G. Vettolani and A. Zanichelli and C. Adami and S. Arnouts and S. Bardelli and M. Bolzonella and A. Bongiorno and A. Cappi and S. Charlot and P. Ciliegi and T. Contini and O. Cucciati and S. de la Torre and K. Dolag and S. Foucaud and P. Franzetti and I. Gavignaud and O. Ilbert and A. Iovino and F. Lamareille and B. Marano and A. Mazure and P. Memeo and R. Merighi and L. Moscardini and S. Paltani and R. Pello and E. Perez-Montero and L. Pozzetti and M. Radovich and D. Vergani and G. Zamorani and E. Zucca},
journal= {arXiv preprint arXiv:0802.1944},
year = {2009}
}
Comments
One PDF file including both main paper and Supplementary Information (28 pages, 3+2 figures). Published version available at http://www.nature.com/nature/journal/v451/n7178/abs/nature06555.html