Relic gravitational waves in light of the 7-year Wilkinson Microwave Anisotropy Probe data and improved prospects for the Planck mission
- School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA (United Kingdom)
The new release of data from Wilkinson Microwave Anisotropy Probe improves the observational status of relic gravitational waves. The 7-year results enhance the indications of relic gravitational waves in the existing data and change to the better the prospects of confident detection of relic gravitational waves by the currently operating Planck satellite. We apply to WMAP7 data the same methods of analysis that we used earlier [W. Zhao, D. Baskaran, and L. P. Grishchuk, Phys. Rev. D 80, 083005 (2009)] with WMAP5 data. We also revised by the same methods our previous analysis of WMAP3 data. It follows from the examination of consecutive WMAP data releases that the maximum likelihood value of the quadrupole ratio R, which characterizes the amount of relic gravitational waves, increases up to R=0.264, and the interval separating this value from the point R=0 (the hypothesis of no gravitational waves) increases up to a 2{sigma} level. The primordial spectra of density perturbations and gravitational waves remain blue in the relevant interval of wavelengths, but the spectral indices increase up to n{sub s}=1.111 and n{sub t}=0.111. Assuming that the maximum likelihood estimates of the perturbation parameters that we found from WMAP7 data are the true values of the parameters, we find that the signal-to-noise ratio S/N for the detection of relic gravitational waves by the Planck experiment increases up to S/N=4.04, even under pessimistic assumptions with regard to residual foreground contamination and instrumental noises. We comment on theoretical frameworks that, in the case of success, will be accepted or decisively rejected by the Planck observations.
- OSTI ID:
- 21420901
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 82, Issue 4; Other Information: DOI: 10.1103/PhysRevD.82.043003; (c) 2010 American Institute of Physics; ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANISOTROPY
DENSITY
DISTURBANCES
GRAVITATIONAL WAVES
HYPOTHESIS
MAXIMUM-LIKELIHOOD FIT
MICROWAVE RADIATION
NOISE
PERTURBATION THEORY
RELICT RADIATION
SIGNAL-TO-NOISE RATIO
SPECTRA
WAVELENGTHS
DIMENSIONLESS NUMBERS
ELECTROMAGNETIC RADIATION
MATHEMATICAL SOLUTIONS
NUMERICAL SOLUTION
PHYSICAL PROPERTIES
RADIATIONS