Using WMAP 3-year data at the locations of close to $sim 700$ X-ray selected clusters we have detected the amplitude of the thermal Sunyaev-Zeldovich (TSZ) effect at the 15$sigma$ level, the highest statistical significance reported so far. Owing to
the large size of our cluster sample, we are able to detect the corresponding CMB distortions out to large cluster-centric radii. The region over which the TSZ signal is detected is, on average, four times larger in radius than the X-ray emitting region, extending to $sim 3h_{70}^{-1}$Mpc. We show that an isothermal $beta$ model does not fit the electron pressure at large radii; instead, the baryon profile is consistent with the Navarro-Frenk-White profile, expected for dark matter in the concordance $Lambda$CDM model. The X-ray temperature at the virial radius of the clusters falls by a factor $sim 3-4$ from the central value, depending on the cluster concentration parameter. Our results suggest that cluster dynamics at large radii is dominated by dark matter and is well described by Newtonian gravity.
If the gas in filaments and halos shares the same velocity field than the luminous matter, it will generate measurable temperature anisotropies due to the Kinematic Sunyaev-Zeldovich effect. We compute the distribution function of the KSZ signal prod
uced by a typical filament and show it is highly non-gaussian. The combined contribution of the Thermal and Kinematic SZ effects of a filament of size $Lsimeq 5$Mpc and electron density $n_esimeq 10^3m^{-3}$ could explain the cold spots of $deltasim -200mu$K on scales of 30 found in the Corona Borealis Supercluster by the VSA experiment. PLANCK, with its large resolution and frequency coverage, could provide the first evidence of the existence of filaments in this region. The KSZ contribution of the network of filaments and halo structures to the radiation power spectrum peaks around $lsim 400$, a scale very different from that of clusters of galaxies, with a maximum amplitude $l(l+1)C_l/2pisim 10-25 (mu K)^2$, depending on model parameters, i.e., $sigma_8$ and the Jeans length. About 80% of the signal comes from filaments with redshift $zle 0.1$. Adding this component to the intrinsic Cosmic Microwave Background temperature anisotropies of the concordance model improves the fit to WMAP 3yr data by $Deltachi^2simeq 1$. The improvement is not statistically significant but a more systematic study could demonstrate that gas could significantly contribute to the anisotropies measured by WMAP.
