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.

E.V. Arbuzova, A.D. Dolgov, L. A. Panasenko

Equation describing propagation of gravitational waves (GW) over arbitrary curved space-time background is analyzed. A new term, which is absent in the conventional homogeneous and isotropic Friedmann cosmology, is found. Some examples of realistic metric, where this new term manifests itself, are presented. Possible implications to very low frequency GW are briefly discussed.

Pavel Jiroušek, Keigo Shimada, Alexander Vikman, Masahide Yamaguchi

We show that promoting the trace part of the Einstein equations to a trivial identity results in the Newton constant being an integration constant. Thus, in this formulation the Newton constant is a global dynamical degree of freedom which is also a subject to quantization and quantum fluctuations. This is similar to what happens to the cosmological constant in the unimodular gravity where the trace part of the Einstein equations is lost in a different way. We introduce a constrained variational formulation of these modified Einstein equations. Then, drawing on analogies with the Henneaux- Teitelboim action for unimodular gravity, we construct different general-covariant actions resulting in these dynamics. The inverse of dynamical Newton constant is canonically conjugated to the Ricci scalar integrated over spacetime. Surprisingly, instead of the dynamical Newton constant one can formulate an equivalent theory with a dynamical Planck constant. Finally, we show that an axion-like field can play a role of the Newton constant or the Planck constant.