BB cross-spectra 𝒟_ℓ(ν₁ × ν₂) versus the effective frequency ν_eff = (ν₁ × ν₂)^0.5, for the LR62 sky region and two multipole bins: ℓ = 4-11 (top plot) and 40–59 (bottom). Yellow and blue colours represent data values from single and inter-frequency cross spectra, respectively. Bottom panel: within each plot shows the residuals from the fits normalized to the 1 σ uncertainty of each data point. Lower frequency data (left) points are dominated by the SED of synchrotron polarized emission, while higher frequency (right) data characterize dust polarized emission, and those at the centre characterize the correlation between the two sources of emission. Differences between the two plots illustrate that both the ratio between synchrotron and dust power and the correlation between these two sources of polarized emission decrease for increasing multipoles.