The Microwave Anisotropy Probe Mission Bennett, C. L; Bay, M; Halpern, M ...
The Astrophysical journal,
01/2003, Letnik:
583, Številka:
1
Journal Article
The WMAP satellite has completed 3 years of observations of the cosmic microwave background radiation. The 3 year data products include several sets of full sky maps of the Stokes I, Q, and U ...parameters in five frequency bands, spanning 23-94 GHz, and supporting items such as beam window functions and noise covariance matrices. The processing used to produce the current sky maps and supporting products represents a significant advancement over the first-year analysis and is described herein. Improvements to the pointing reconstruction, radiometer gain modeling, window function determination, and radiometer spectral noise parameterization are presented. A detailed description of the updated data processing that produces maximum likelihood sky map estimates is presented, along with the methods used to produce reduced resolution maps and corresponding noise covariance matrices. Finally, two methods used to evaluate the noise of the full resolution sky maps are presented along with several representative year-to-year null tests, demonstrating that sky maps produced from data from different observational epochs are consistent.
Cosmology and other scientific results from the Wilkinson Microwave Anisotropy Probe (WMAP) mission require an accurate knowledge of the beam patterns in flight. While the degree of beam knowledge ...for the WMAP one-year and three-year results was unprecedented for a CMB experiment, we have significantly improved the beam determination as part of the five-year data release. Physical optics fits are done on both the A and the B sides for the first time. The cutoff scale of the fitted distortions on the primary mirror is reduced by a factor of ~2 from previous analyses. These changes enable an improvement in the hybridization of Jupiter data with beam models, which is optimized with respect to error in the main beam solid angle. An increase in main-beam solid angle of ~1% is found for the V2 and W1-W4 differencing assemblies. Although the five-year results are statistically consistent with previous ones, the errors in the five-year beam transfer functions are reduced by a factor of ~2 as compared to the three-year analysis. We present radiometry of the planet Jupiter as a test of the beam consistency and as a calibration standard; for an individual differencing assembly, errors in the measured disk temperature are ~0.5%.
The first-year Wilkinson Microwave Anisotropy Probe (WMAP) data, in combination with any one of a number of other cosmic probes, show that we live in a flat lambda -dominated cold dark matter (CDM) ...universe with Omega sub(m) ~ 0.27 and Omega sub( lambda ) ~ 0.73. In this model the late- time action of the dark energy, through the integrated Sachs-Wolfe effect, should produce cosmic microwave background (CMB) anisotropies correlated with matter density fluctuations at z ~ 2 (Crittenden & Turok 1996). The measurement of such a signal is an important independent check of the model. We cross-correlate the NRAO VLA Sky Survey (NVSS) radio source catalog (Condon et al. 1998) with the WMAP data in search of this signal, and see indications of the expected correlation. Assuming a flat lambda CDM cosmology, we find Omega sub( lambda ) > 0 (95% CL, statistical errors only) with the peak of the likelihood at Omega sub( lambda ) = 0.68, consistent with the preferred WMAP value. A closed model with Omega sub(m) = 1.28, h = 0.33, and no dark energy component (Omega sub( lambda ) = 0), marginally consistent with the WMAP CMB TT angular power spectrum, would produce an anticorrelation between the matter distribution and the CMB. Our analysis of the cross-correlation of the WMAP data with the NVSS catalog rejects this cosmology at the 3 capital sigma level.
Microwave SQUID multiplexing is a promising technique for multiplexing large arrays of transition edge sensors. A major bottleneck in the development and distribution of microwave SQUID multiplexer ...chips occurs in the time-intensive design testing and quality assurance stages. To obtain useful RF measurements, these devices must be cooled to temperatures below 500 mK. The need for a more efficient system to screen microwave multiplexer chips has grown as the number of chips requested by collaborators per year reaches into the hundreds. We have therefore assembled a test bed for microwave SQUID circuits, which decreases screening time for four 32-channel chips from 24 h in an adiabatic demagnetization refrigerator to approximately 5 h in a helium dip probe containing a closed cycle
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He sorption refrigerator. We discuss defining characteristics of these microwave circuits and the challenges of establishing an efficient testing setup for them.
We present cosmological parameter constraints based on the final nine-year Wilkinson Microwave Anisotropy Probe (WMAP) data, in conjunction with a number of additional cosmological data sets. The ...WMAP data alone, and in combination, continue to be remarkably well fit by a six-parameter ?CDM model. We compare recent Planck measurements of the Sunyaev-Zel'dovich effect with our seven-year measurements, and show their mutual agreement. Our analysis of the polarization pattern around temperature extrema is updated. This confirms a fundamental prediction of the standard cosmological model and provides a striking illustration of acoustic oscillations and adiabatic initial conditions in the early universe.
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