Bayesian recalibration of Planck galaxy cluster scaling relations including relativistic Sunyaev-Zel'dovich corrections

Abstract: We investigate the impact of relativistic SZ corrections on Planck measurements of massive galaxy clusters, finding that they have a significant impact at the $\approx$5 -- 15% and up to $\approx 3\sigma$ level. We investigate the possibility of constraining temperature directly from these SZ measurements but find that only weak constraints are possible for the most significant detections; for most clusters, an external temperature measurement is required to correctly measure integrated Compton-$y$. We also investigate the impact of profile shape assumptions and find that these have a small but non-negligible impact on measured Compton-$y$, at the $\approx$5% level. Informed by the results of these investigations, we recalibrate the Planck SZ observable-mass scaling relation, using the updated NPIPE data release and a larger sample of X-ray mass estimates. Along with the expected change in the high-mass end of the scaling relation, which does not impact Planck mass estimation, we also find hints of a low-mass deviation but this requires better understanding of the selection function in order to confirm.