First constraints on the intrinsic CMB dipole and our velocity with Doppler and aberration.- [PDF] - [Article]

Pedro da Silveira Ferreira, Miguel Quartin

The CMB dipole is usually assumed to be completely due to the relative velocity between the solar system and the CMB restframe. We test this hypothesis by measuring independently the Doppler and aberration effects on the CMB using Planck 2018 data. We remove the contributions arising solely from the conversion of intensity into temperature and arrive at measurements which are independent from the CMB dipole itself. Doppler and aberration are measured independently in the TT and EE maps for both SMICA and NILC. Combining these new measurements with the dipole one we get the first constraints on the intrinsic CMB dipole. Neglecting a dipolar lensing contribution we can put an upper limit on its amplitude: 3.5 mK (95% CI). We also obtain the estimate of the peculiar velocity of the solar system which does not assume a negligible intrinsic dipole contribution: $v = (300 \pm 99)$ km/s with $(l,b) = (276 \pm 32, 51 \pm 19)^\circ$ [SMICA] and $v = (300 \pm 100)$ km/s with $(l,b) = (280 \pm 32, 50 \pm 20)^\circ$ [NILC] with negligible systematic contributions. These values are consistent with the peculiar velocity hypothesis of the dipole.