Disentangling Doppler modulation, aberration and the temperature dipole in the CMB

Understand

An observer in relative motion to the Cosmic Microwave Background (CMB) rest frame is sensitive to both aberration and Doppler effects.

• Both effects introduce similar but non-identical off-diagonal couplings in the spherical harmonic coefficients.
• The CMB temperature dipole may have additional contributions from an intrinsic component, which in turn produces different aberration and Doppler couplings.
• Moreover, the standard conversion from intensity measurements into temperature also introduces spurious Doppler-like couplings.