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SCI-BYTES - WHAT'S NEW IN RESEARCH : 2009

Week of March 15, 2009 < Back ¦ 2009 ¦ Home

 
Hot Paper in Physics

"Three-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: Implications for cosmology," by D.N. Spergel and 21 others, Astrophysical Journal Supplement Series, 170(2): 377-408, June 2007.

[Authors' affiliations: 13 U.S. and Canadian institutions]

Abstract: "A simple cosmological model with only six parameters (matter density, Omega(m)h(2), baryon density, Omega(b)h(2), Hubble constant, H-0, amplitude of fluctuations, sigma(8), optical depth, tau, and a slope for the scalar perturbation spectrum, n(s)) fits not only the 3 year WMAP temperature and polarization data, but also small-scale CMB data, light element abundances, large-scale structure observations, and the supernova luminosity/distance relationship. Using WMAP data only, the best-fit values for cosmological parameters for the power-law flat Lambda cold dark matter (Lambda CDM) model are (Omega(m)h(2), Omega(b)h(2), h, n(s), tau, sigma(s)) = (0.1277(-0.0079)(+0.0080), 0.02229 +/- 0.00073, 0.732(-0.032)(+0.031), 0.958 +/- 0.016, 0.089 +/- 0.030, 0.761(-0.048)(+0.049)). The 3 year data dramatically shrink the allowed volume in this six-dimensional parameter space. Assuming that the primordial fluctuations are adiabatic with a power-law spectrum, the WMAP data alone require dark matter and favor a spectral index that is significantly less than the Harrison-Zel'dovich-Peebles scale-invariant spectrum ( n(s) = 1, r = 0). Adding additional data sets improves the constraints on these components and the spectral slope. For power-law models, WMAP data alone puts an improved upper limit on the tensor-to-scalar ratio, r(0.002) < 0.65 ( 95% CL) and the combination of WMAP and the lensing-normalized SDSS galaxy survey implies r(0.002) < 0.30 ( 95% CL). Models that suppress large-scale power through a running spectral index or a large-scale cutoff in the power spectrum are a better fit to the WMAP and small-scale CMB data than the power-law Lambda CDM model; however, the improvement in the fit to the WMAP data is only Delta(2)(chi) = 3 for 1 extra degree of freedom. Models with a running-spectral index are consistent with a higher amplitude of gravity waves. In a flat universe, the combination of WMAP and the Supernova Legacy Survey (SNLS) data yields a significant constraint on the equation of state of the dark energy, w = -0.967(-0.072)(+0.073). If we assume w = -1, then
the deviations from the critical density, Omega(K), are small: the combination of WMAP and the SNLS data implies Omega(k) = -0.011 +/- 0.012. The combination of WMAP 3 year data plus the HST Key Project constraint on H-0 implies Omega(k) = -0.014 +/- 0.017 and Omega(Lambda) = 0.716 +/- 0.055. Even if we do not include the prior that the universe is flat, by combining WMAP, large-scale structure, and supernova data, we can still put a strong constraint on the dark energy equation of state, w = -1.08 +/- 0.12. For a flat universe, the combination of WMAP and other astronomical data
yield a constraint on the sum of the neutrino masses, Sigma m(nu) < 0.66 eV (95%CL). Consistent with the predictions of simple inflationary theories, we detect no significant deviations from Gaussianity in the CMB maps using Minkowski functionals, the bispectrum, trispectrum, and a new statistic designed to detect large-scale anisotropies in the fluctuations."

This 2007 report from Astrophysical Journal Supplement Series was cited 138 times in current journal articles indexed by Clarivate Analytics
during November-December 2008. This latest two-month total, although down a bit from previous counts, was more than sufficient to extend the report's status for an eighth consecutive bimonthly period as the most-cited physics paper published in the last two years. Prior to the most recent tally, citations to the paper have accrued as follows:

September-October 2008: 170 citations
July-August 2008: 217
May-June 2008: 148
March-April 2008: 201
January-February 2008: 160
November-December 2007: 116
September-October 2007: 107
July-August 2007: 6

Total citations to date: 1,263


SOURCE: Hot Papers Database (Included with a subscription to the print newsletter Science Watch®, available from the Research Services Group of Thomson Reuters. Packaged on a CD that is mailed with each Science Watch issue, the Hot Papers Database contains data on hundreds of highly cited papers published during the last two years. User interface permits searching by author, organization, journal, field, and more. Total citations, as well as citations accrued during successive bimonthly periods, can be assessed and graphed. An updated CD containing the most recent bimonthly data is mailed with every new issue of Science Watch, six times a year. The CD also includes an electronic version of the Science Watch issue in HTML format, for personal desktop access.

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