We present a multiwavelength analysis of a sample of four hot (T X > 8 keV) X-ray galaxy clusters (A1689, A2261, A2142, and A2390) using joint AMiBA Sunyaev-Zel'dovich effect (SZE) and Subaru weak lensing observations, combined with published X-ray temperatures, to examine the distribution of mass and the intracluster medium (ICM) in massive cluster environments. Our observations show that A2261 is very similar to A1689 in terms of lensing properties. Many tangential arcs are visible around A2261, with an effective Einstein radius ∼ 40 ′′ (at z ∼ 1.5), which when combined with our weak lensing measurements implies a mass profile well fitted by an NFW model with a high concentration c vir ∼ 10, similar to A1689 and to other massive clusters. The cluster A2142 shows complex mass substructure, and displays a shallower profile (c vir ∼ 5), consistent with detailed X-ray observations which imply recent interaction. The AMiBA map of A2142 exhibits an SZE feature associated with mass substructure lying ahead of the sharp north-west edge of the X-ray core suggesting a pressure increase in the ICM. For A2390 we obtain highly elliptical mass and ICM distributions at all radii, consistent with other X-ray and strong lensing work. Our cluster gas fraction measurements, free from the hydrostatic equilibrium assumption, are overall in good agreement with published X-ray and SZE observations, with the sample-averaged gas fraction of f gas (< r 200 ) = 0.133 ± 0.027, for our sample with M vir = (1.2 ± 0.1) × 10 15 M ⊙ h −1 . When compared to the cosmic baryon fraction f b = Ω b /Ω m constrained by the WMAP 5-year data, this indicates f gas,200 / f b = 0.78 ± 0.16, i.e., (22 ± 16)% of the baryons are missing from the hot phase of clusters.

We give a full analysis of the auto-and cross-correlations between the Stokes parameters of the cosmic microwave background. In particular, we derive the windowing function for an antenna with Gaussian response in polarization experiment, and construct correlation function estimators corrected for instrumental noise. They are applied to calculate the signal to noise ratios for future anisotropy and polarization measurements. While the small-angular-scale anisotropy-polarization correlation would be likely detected by the MAP satellite, the detection of electric and magnetic polarization would require higher experimental sensitivity. For large-angular-scale measurements such as the being planned SPOrt/ISS, the expected signal to noise ratio for polarization is greater than one only for reionized models with high reionization redshifts, and the ratio is less for anisotropypolarization correlation. Correlation and covariance matrices for likelihood analyses of ground-based and satellite data are also given.

We present the full set of power spectra of cosmic microwave background (CMB) temperature and polarization anisotropies due to the coupling between quintessence and pseudoscalar of electromagnetism. This coupling induces a rotation of the polarization plane of the CMB, thus resulting in a nonvanishing B mode and parity-violating TB and EB modes. Using the BOOMERANG data from the flight of 2003, we derive the most stringent constraint on the coupling strength. We find that in some cases the rotation-induced B mode can confuse the hunting for the gravitational lensing-induced B mode.

We consider the effect of three species of neutrinos with nearly degenerate mass on the cosmic structure formation in a low matter-density universe within a hierarchical clustering scenario with a flat initial perturbation spectrum. The matching condition for fluctuation powers at the COBE scale and at the cluster scale leads to a strong upper limit on neutrino mass. For a flat universe with matter density parameter Ω = 0.3, we obtain mν < 0.6 eV for the Hubble constant H0 < 80 km s −1 Mpc −1 . Allowing for the more generous parameter space limited by Ω < 0.4, H0 < 80 km s −1 Mpc −1 and age t0 > 11.5 Gyr, the limit is 0.9 eV.14.60. Pq, 98.80.Es Recent experiments for atmospheric and solar neutrino fluxes suggest that the neutrinos are massive. In particular, the atmospheric neutrino experiment indicates an almost maximal mixing between the two neutrinos, which is most naturally understood if the relevant species are nearly degenerate in mass. Nearly maximal mixing is also a viable possibility to explain the long-standing solar neutrino problem with oscillation either in vacuum or in matter, although there remains the solution that it is explained by small-angle mixing via oscillation in matter [1]. For these reasons the idea has gained popularity that the three neutrinos are massive and almost degenerate in mass (e.g., [1,2]). The degenerate neutrinos mean that neutrino mass is larger than several tenths of eV, and this means that they provide the universe with a matter density comparable to or more than that in stars, and play some role in cosmological structure formation.There are a few authors who discussed the possibility that neutrinos have played an active role in the formation of large-scale structure of the universe, especially in giving a power at a large scale which otherwise cannot be accounted for in the standard cold dark matter scenario at the critical matter density [3]. At the time of the emergence of this idea theorists took more seriously the Einstein-de Sitter (EdS) universe of the critical matter density, so that typical compositions of the matter were assumed to be Ω CDM = 0.7 − 0.8 and Ω ν = 0.3 − 0.2 in units of the closure density, 10.54h 2 keV (cm) −3 , where h is the Hubble constant H 0 in units of 100 km s −1 Mpc −1 . This neutrino mass density corresponds to neutrino mass of (30 − 20)h 2 eV. There have been many explorations of this scenario since the proposal [4], and the current conclusion is that the neutrino density in excess of Ω ν ≥ 0.3 is disfavoured in the EdS universe from the viewpoint of early cosmic structure formation.Over the last few years the evidence has been accumulated indicating a low density universe. There are also observations pointing to the dominance of the vacuum energy (cosmological constant, Λ) that makes universe's curvature flat, which is also preferred from theoretical point of view for a low matter density universe. The list in favour of a low matter-density universe includes: (1) Hubble constant -cosmic age mismatch for the Ω = 1 universe; (2) No po...

The secondary anisotropies and polarization of the Cosmic Microwave Background (CMB) provide a laboratory for the study of the epoch of reionization in the Universe. Here, we concentrate on the CMB polarization in models with inhomogeneous reionization. Although the amplitude of the polarization anisotropy is estimated to be much smaller than that in the temperature, it is advantageous to consider the polarization signal since it is generated when photons and electrons scatter for the last time. Detection of these signals will place important contraints on the reionization history of the Universe. CP609, Astrophysical Polarized Backgrounds, edited by S. Cecchini eta!.