Subdegree Sunyaev-Zel'dovich Signal from Multifrequency BOOMERANG Observations

The Sunyaev-Zel'dovich (SZ) effect is the inverse Compton-scattering of cosmic microwave background (CMB) photons by hot electrons in the intervening gas throughout the universe. The effect has a distinct spectral signature that allows its separation from other signals in multifrequency CMB data sets. Using CMB anisotropies measured at three frequencies by the BOOMERanG 2003 flight we constrain SZ fluctuations in the 10 arcmin to 1 deg angular range. Propagating errors and potential systematic effects through simulations, we obtain an overall upper limit of 15.3 mu K (2 sigma) for rms SZ fluctuations in a broad bin between multipoles of 250 and 1200 at the Rayleigh-Jeans (RJ) end of the spectrum. The resulting upper limit on the local universe normalization of the density perturbations with BOOMERanG SZ data alone is sigma(SZ)(8) < 1.14 at the 95% confidence level. When combined with other CMB anisotropy and SZ measurements, we find sigma(SZ)(8) < 0.92 (95% c. l.).