What is the likely limit to a B-mode detection set by Galactic foregrounds ?

where the spectral index β is related to p through β = − 2 . β ∼ −3 is observed at microwave frequencies. The linear polarization fraction is at most (in a uniform ~ B field) fs = p+1 p+7/3 ∼ 0.75 for β ∼ −3. The parameter C indicates possible deviations from a pure power-law. Of course, all this is dependent on the position on the sky, i.e one really has Ts(ν0, n̂), β(n̂), C(n̂). The polarization angle is also dependent on the position on the sky.