Massive redshift surveys of galaxies beyond the local Universe (i.e. z > 0.3) provide an exhaustive probe of the observed acceleration of cosmic expansion. While they have the ability to measure the expansion history H(z) through Baryonic Acoustic Oscillations in the galaxy power spectrum, they can at the same time probe f(z) using the redshift-space distortions introduced in the observed clustering pattern by galaxy peculiar motions. Coupling these two measurements one can in principle distinguish whether cosmic acceleration is due to a new form of 'dark energy' in the cosmic budget, or rather requires a modification of General Relativity. These two radically alternative scenarios are degenerate when considering H (z) alone, as yielded, e.g., by the Hubble diagram of Type la supernovae. We review our recent measurements of redshift distortions at z similar to 1 based on the VIMOS VLT Deep Survey "Wide" data and discuss the revived interest on this technique in the context of dark energy. Current results are consistent with the simplest cosmological-constant scenario, but error bars are still too large to rule out alternative models. Forecasts based both on extensive simulations and Fisher-matrix computations, show that next-generation deep surveys optimizing the combination of large volumes and good galaxy sampling will be able to use redshift distortions as a key tool to understand the physical origin of cosmic acceleration. Among these, we introduce the newly started VIMOS Public Extragalactic Redshift Survey (VIPERS) at the ESO VLT, which is building at < z > similar to 0.8 a sample comparable to current local redshift surveys (10(5) redshifts in a volume 5 x 10(7) h(-1) Mpc(3)). Finally, we provide an example of the exquisite accuracy that could be reached on measurements of redshift-space distortions (among many others), with a massive 20,000 deg(2) near-infrared spectroscopic survey from space, as foreseen by the EUCLID mission for the ESA 'Cosmic Vision' program.
Redshift-space distortions in deep redshift surveys as a probe of the invisible universe / L. Guzzo, O. Le Fèvre (AIP CONFERENCE PROCEEDINGS). - In: Invisible universe: Proceedings / [a cura di] J.-M. Alimi, A. Fuözfa. - [s.l] : AIP Publishing, 2010. - ISBN 9780735407893. - pp. 39-45 (( convegno Invisible Universe International Conference tenutosi a Paris nel 2009.
Redshift-space distortions in deep redshift surveys as a probe of the invisible universe
L. Guzzo;
2010
Abstract
Massive redshift surveys of galaxies beyond the local Universe (i.e. z > 0.3) provide an exhaustive probe of the observed acceleration of cosmic expansion. While they have the ability to measure the expansion history H(z) through Baryonic Acoustic Oscillations in the galaxy power spectrum, they can at the same time probe f(z) using the redshift-space distortions introduced in the observed clustering pattern by galaxy peculiar motions. Coupling these two measurements one can in principle distinguish whether cosmic acceleration is due to a new form of 'dark energy' in the cosmic budget, or rather requires a modification of General Relativity. These two radically alternative scenarios are degenerate when considering H (z) alone, as yielded, e.g., by the Hubble diagram of Type la supernovae. We review our recent measurements of redshift distortions at z similar to 1 based on the VIMOS VLT Deep Survey "Wide" data and discuss the revived interest on this technique in the context of dark energy. Current results are consistent with the simplest cosmological-constant scenario, but error bars are still too large to rule out alternative models. Forecasts based both on extensive simulations and Fisher-matrix computations, show that next-generation deep surveys optimizing the combination of large volumes and good galaxy sampling will be able to use redshift distortions as a key tool to understand the physical origin of cosmic acceleration. Among these, we introduce the newly started VIMOS Public Extragalactic Redshift Survey (VIPERS) at the ESO VLT, which is building at < z > similar to 0.8 a sample comparable to current local redshift surveys (10(5) redshifts in a volume 5 x 10(7) h(-1) Mpc(3)). Finally, we provide an example of the exquisite accuracy that could be reached on measurements of redshift-space distortions (among many others), with a massive 20,000 deg(2) near-infrared spectroscopic survey from space, as foreseen by the EUCLID mission for the ESA 'Cosmic Vision' program.
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