Integrated Sachs-Wolfe effect from the cross correlation of WMAP 3 year and the NRAO VLA sky survey data: New results and constraints on dark energy
- Dipartimento di Fisica, Universita di Roma 'Tor Vergata', V. della Ricerca Scientifica 1, I-00133 Roma (Italy)
- Dipartimento di Fisica, Universita di Roma 'Tor Vergata' and INFN Sezione di Roma 'Tor Vergata', V. della Ricerca Scientifica 1, I-00133 Rome (Italy)
- Dipartimento di Matematica, Universita di Roma 'Tor Vergata', V. della Ricerca Scientifica 1, I-00133 Rome (Italy)
We cross correlate the new 3 year Wilkinson Microwave Anistropy Probe (WMAP) cosmic microwave background data with the NRAO VLA Sky Survey radio galaxy data and find further evidence of late integrated Sachs-Wolfe (ISW) effect taking place at late times in cosmic history. Our detection makes use of a novel statistical method (P. Baldi, G. Kerkyacharian, D. Marinucci, and D. Picard, math.ST/0606154 and P. Baldi, G. Kerkyacharian, D. Marinucci, D. Picard, math.ST/0606599) based on a new construction of spherical wavelets, called needlets. The null hypothesis (no ISW) is excluded at more than 99.7% confidence. When we compare the measured cross correlation with the theoretical predictions of standard, flat cosmological models with a generalized dark energy component parameterized by its density, {omega}{sub DE}, equation of state w and speed of sound c{sub s}{sup 2}, we find 0.3{<=}{omega}{sub DE}{<=}0.8 at 95% C.L., independently of c{sub s}{sup 2} and w. If dark energy is assumed to be a cosmological constant (w=-1), the bound on density shrinks to 0.41{<=}{omega}{sub DE}{<=}0.79. Models without dark energy are excluded at more than 4{sigma}. The bounds on w depend rather strongly on the assumed value of c{sub s}{sup 2}. We find that models with more negative equation of state (such as phantom models) are a worse fit to the data in the case c{sub s}{sup 2}=1 than in the case c{sub s}{sup 2}=0.
- OSTI ID:
- 20870970
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 74, Issue 4; Other Information: DOI: 10.1103/PhysRevD.74.043524; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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