A Limit on the Polarized Anisotropy of the Cosmic Microwave Background at Subdegree Angular Scales

A ground-based polarimeter, PIQUE, operating at 90 GHz has set a new limit on the magnitude of any polarized anisotropy in the cosmic microwave background. The combination of the scan strategy and full width half-maximum beam of 0 24 gives broad window functions with ⟨ l E ⟩ = 211 and ⟨ l B ⟩ = 212 for the E - and B -mode window functions, respectively. A joint likelihood analysis yields simultaneous 95% confidence level flat band power limits of 14 and 13 μK on the amplitudes of the E - and B -mode angular power spectra, respectively. Assuming no B -modes, a 95% confidence limit of 10 μK is placed on the amplitude of the E -mode angular power spectrum alone.