What's New in Research: December 27, 2004
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"First-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of cosmological parameters," by D.N. Spergel and 16 others, Astrophysical Journal Supplement Series, 148(1): 175-94, September 2003. [Authors' affiliations: 6 U.S. and Canadian institutions]
Related information:
by lead-author David N. Spergel about this paper
by co-author Licia Verde about this paper

Abstract: "WMAP precision data enable accurate testing of cosmological models. We find that the emerging standard model of cosmology, a flat Lambda-dominated universe seeded by a nearly scale-invariant adiabatic Gaussian fluctuations, fits the WMAP data. For the WMAP data only, the best-fit parameters are h=0.72+/-0.05,
Omega(b)h(2)=0.024+/-0.001, Omega(m)h(2)=0.14+/-0.02, tau=0.166(-0.081)(+0.076), n(s)=0.99+/-0.04, and sigma(8)=0.9+/-0.1. With parameters fixed only by WMAP data, we can fit finer scale cosmic microwave background (CMB) measurements and measurements of large-scale structure (galaxy surveys and the Lyalpha forest). This simple model is also consistent with a host of other astronomical measurements: its inferred age of the universe is consistent with stellar ages, the baryon/photon ratio is consistent with measurements of the [D/H] ratio, and the inferred Hubble constant is consistent with local observations of the expansion rate. We then fit the model parameters to a combination of WMAP data with other finer scale CMB experiments (ACBAR and CBI), 2dFGRS measurements, and Lyalpha forest data to find the model's best-fit cosmological parameters: h=0.71(-0.03)(+0.04), Omega(b)h(2)=0.0224+/-0.0009, Omega(m)h(2)=0.135(-0.009)(+0.008), tau=0.17+/-0.06, n(s)(0.05 Mpc(-1))=
0.93+/-0.03, and sigma(8)=0.84+/-0.04. WMAP's best determination of tau=0.17+/-0.04 arises directly from the
temperature-polarization (TE) data and not from this model fit, but they are consistent. These parameters imply that the age of the universe is 13.7+/-0.2 Gyr. With the Lyalpha forest data, the model favors but does not require a slowly varying spectral index. The significance of this running index is sensitive to the uncertainties in the Lyalpha forest. By combining WMAP data with other astronomical data, we constrain the geometry of the universe, Omega(tot)= 1.02+/-0.02, and the equation of state of the dark energy, w<-0.78 (95% confidence limit assuming w&GE;-1). The combination of WMAP and 2dFGRS data constrains the energy density in stable neutrinos: &UOmega;(&nu;) h(2)<0.0072 (95% confidence limit). For three degenerate neutrino species, this limit implies that their mass is less than 0.23 eV (95% confidence limit). The WMAP detection of early reionization rules out warm dark matter."

This 2003 report from Astrophysical Journal Supplement Series was cited 174 times in current journal
articles indexed in the Thomson Scientific database during September-October 2004. This now marks the
sixth bimonthly tally in a row in which this report has emerged as the most-cited physics paper published in
the last two years, aside from reviews. This time, in fact, the paper surpasses all of the 1,500 or so reports
in the latest bimonthly update of the Hot Papers file (reviews and all), scoring the most citations of any paper
in all of science published since the fall of 2002. Prior to the most recent two-month tally, its citations have
accrued as follows:

July-August 2004: 144 citations
May-June 2004: 105
March-April 2004: 105
January-February 2004: 102
November-December 2003: 66
September-0ctober 2003: 28

Total citations to date: 724

Related information:
by lead-author David N. Spergel about this paper
by co-author Licia Verde about this paper

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