Shallower radius valley around low-mass hosts provides evidence for icy planets or collisions

The characteristics of the radius valley (i.e. an observed lack of planets between 1.5-2 Earth radii) provide insights into planet formation and evolution. We present a novel view of the radius valley, by refitting the transits of over 500 planets and updating their planetary parameters homogeneously using Kepler 1-minute short cadence data, the vast majority of which have not been previously analysed in this way. With the updated planetary parameters, we find a deeper FGK radius valley compared to several other observations, suggesting that planets are likely to have a more homogeneous core composition at formation. We also observe that the radius valley becomes shallower towards lower mass M-dwarfs, and upon rigorous comparison, we find that these observations are inconsistent with theoretical models of photoevaporation, highlighting evidence for icy planets or collision events for low-mass stars.