Observation and theory of the kinematic matter dipole

Measurements of the cosmic matter dipole offer a foundational consistency check of the standard cosmological model, as per the direct comparison between the rest frames of matter and radiation they enable. Recent observations hint at a significant discrepancy between these frames, which equates to a violation of the cosmological principle, upon which the standard model rests. With upcoming data offering evermore opportunities to understand this observation, detailed theoretical understanding too is required of the used estimators and their ability to describe a realistic experiment. In my talk I will cover both, observational aspects, and theoretical developments. I will explain details of our dipole measurements using radio and mid-infrared AGN samples, how to control for systematics, and what can be learnt from their combination. And I will also report on theoretical insights developed recently, for example those which will prove instructive for anticipated redshift-dependent measurements.