A test of the nature of cosmic acceleration using galaxy redshift distortions

L. Guzzo (1, 2) , M. Pierleoni , B. Meneux (3) , E. Branchini , O. Le Fevre (3) , Christian Marinoni (4, 5) , B. Garilli (2, 6, 7, 8, 9) , J. Blaizot (10, 11, 12) , G. de Lucia , A. Pollo (3, 7, 8, 9) , H. J. Mccracken (11) , D. Bottini (2, 6, 7, 8, 9) , V. Le Brun (3) , D. Maccagni (2, 6, 7, 8, 9) , J. P. Picat (13, 14, 15) , R. Scaramella (2, 7, 8, 9, 16) , M. Scodeggio (2, 6, 7, 8, 9) , L. Tresse (3) , G. Vettolani (1, 2) , A. Zanichelli (2, 7, 8, 9, 17) , C. Adami (3) , S. Arnouts (3) , S. Bardelli (2, 9, 8) , M. Bolzonella (2, 18) , A. Bongiorno (2, 18) , A. Cappi (1, 2, 9, 8) , S. Charlot (11, 19) , P. Ciliegi (2, 7, 8, 9) , T. Contini (14, 15) , O. Cucciati (2, 7, 20) , S. de La Torre (2) , K. Dolag , Sylvie Foucaud (3, 6, 7, 8, 9) , P. Franzetti (2, 6, 7, 8, 9) , I. Gavignaud (13, 14, 15, 21) , O. Ilbert (3, 22, 23) , A. Iovino (2, 7, 8, 9) , F. Lamareille (14, 15, 24) , B. Marano (2) , A. Mazure (3) , P. Memeo , R. Merighi (2, 7, 9, 8) , L. Moscardini , S. Paltani (3) , R. Pello (13, 14, 15) , E. Perez-Montero , L. Pozzetti (2, 7, 9, 8) , M. Radovich (2, 8, 9) , D. Vergani (2, 25) , G. Zamorani (2, 7, 8, 9) , E. Zucca (2, 7, 8, 9)

1 IASF-Bo - Istituto di Astrofisica Spaziale e Fisica cosmica - Bologna
2 AUTRES
3 LAM - Laboratoire d'Astrophysique de Marseille
4 CPT - Centre de Physique Théorique - UMR 6207
5 CPT - Centre de Physique Théorique - UMR 7332
6 IASF-MI - Istituto di Astrofisica Spaziale e Fisica Cosmica - Milano
7 OAB - INAF - Osservatorio Astronomico di Brera
8 OABO - INAF - Osservatorio Astronomico di Bologna
9 OAC - INAF - Osservatorio Astronomico di Capodimonte
10 SPhT - Service de Physique Théorique
11 IAP - Institut d'Astrophysique de Paris
12 University of Oxford
13 UMS 831 - Services communs OMP
14 LATT - Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées
15 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
16 OAR - INAF - Osservatorio Astronomico di Roma
17 IRA - Istituto di Radioastronomia [Bologna]
18 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna
19 MPA - Max-Planck-Institut für Astrophysik
20 Dipartimento di Fisica
21 ESO - European Southern Observatory
22 OAB - INAF - Osservatorio Astronomico di Bologna
23 Institut d'Astrophysique et de Géophysique [Liège]
24 OP - Observatoire de Paris - Site de Paris
25 Institute of Liver Studies

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.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Relativité Générale et Cosmologie Quantique [gr-qc]; Physique des Hautes Energies - Théorie [hep-th]

L. Guzzo, M. Pierleoni, B. Meneux, E. Branchini, O. Le Fevre, et al.. A test of the nature of cosmic acceleration using galaxy redshift distortions. Nature, 2008, 451, pp.541-544. ⟨hal-00263619⟩