Geometrical tests of cosmological models

C. Marinoni; A. Saintonge; R. Giovanelli; M. P. Haynes; K. L. Masters; O. Le Fèvre; A. Mazure; P. Taxil; J.-M. Virey

doi:doi:10.1051/0004-6361:20077116

Free access

Issue		A&A Volume 478, Number 1, January IV 2008


Page(s)		43 - 55
Section		Cosmology (including clusters of galaxies)
DOI		http://dx.doi.org/10.1051/0004-6361:20077116

A&A 478, 43-55 (2008)
DOI: 10.1051/0004-6361:20077116

I. Probing dark energy using the kinematics of high redshift galaxies

C. Marinoni¹, A. Saintonge², R. Giovanelli², M. P. Haynes², K. L. Masters³, O. Le Fèvre⁴, A. Mazure⁴, P. Taxil¹, and J.-M. Virey¹

¹ Centre de Physique Théorique (Centre de Physique Théorique is UMR 6207 - "Unité Mixte de Recherche" of CNRS and of the Universities "de Provence", "de la Méditerranée" and "du Sud Toulon-Var" - Laboratory affiliated to FRUMAM (FR 2291).) , CNRS-Université de Provence, Case 907, 13288 Marseille, France
e-mail: marinoni@cpt.univ-mrs.fr
² Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
³ Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02143, USA
⁴ Laboratoire d'Astrophysique de Marseille, UMR 6110, CNRS Université de Provence, 13376 Marseille, France

(Received 17 January 2007 / Accepted 2 August 2007)

Abstract
We suggest to use the observationally measured and theoretically justified correlation between size and rotational velocity of galactic discs as a viable method to select a set of high redshift standard rods which may be used to explore the dark energy content of the universe via the classical angular-diameter test. Here we explore a new strategy for an optimal implementation of this test. We propose to use the rotation speed of high redshift galaxies as a standard size indicator and show how high resolution multi-object spectroscopy and ACS/HST high quality spatial images, may be combined to measure the amplitude of the dark energy density parameter $\Omega_{Q}$ , or to constrain the cosmic equation of state parameter for a smooth dark energy component (w = $p/\rho$ , -1 $\le$ w < -1/3). Nearly 1300 standard rods with high velocity rotation in the bin V = 200 $\pm$ 20 km s^-1 are expected in a field of 1 sq. degree and over the redshift baseline 0 < z < 1.4. This sample is sufficient to constrain the cosmic equation of state parameter w at a level of 20% (without priors in the $[\Omega_{\rm m},\Omega_Q]$ plane) even when the [OII] $\lambda$ 3727 Å linewidth-diameter relationship is calibrated with a scatter of ~40%. We evaluate how systematics may affect the proposed tests, and find that a linear standard rod evolution, causing galaxy dimensions to be up to 30% smaller at z = 1.5, can be uniquely diagnosed, and will minimally bias the confidence level contours in the [ $\Omega_{Q}$ , w] plane. Finally, we show how to derive, without a priori knowing the specific functional form of disc evolution, a cosmology-evolution diagram with which it is possible to establish a mapping between different cosmological models and the amount of galaxy disc/luminosity evolution expected at a given redshift.

Key words: cosmology: observations -- cosmology: theory -- cosmology: cosmological parameters -- galaxies: high-redshift -- galaxies: fundamental parameters -- galaxies: evolution