The redshift evolution of X-ray and Sunyaev-Zel'dovich scaling relations
  in the FABLE simulations
  We study the redshift evolution of the X-ray and Sunyaev-Zel'dovich (SZ)
scaling relations for galaxy groups and clusters in the FABLE suite of
cosmological hydrodynamical simulations. Using an expanded sample of $27$
high-resolution zoom-in simulations, together with a uniformly-sampled
cosmological volume to sample low-mass systems, we find very good agreement
with the majority of observational constraints up to $z \sim 1$. We predict
significant deviations of all examined scaling relations from the simple
self-similar expectations. While the slopes are approximately independent of
redshift, the normalisations evolve positively with respect to self-similarity,
even for commonly-used mass proxies such as the $Y_{\mathrm{X}}$ parameter.
These deviations are due to a combination of factors, including more effective
AGN feedback in lower mass haloes, larger binding energy of gas at a given halo
mass at higher redshifts and larger non-thermal pressure support from kinetic
motions at higher redshifts. Our results have important implications for
cluster cosmology from upcoming SZ surveys such as SPT-3G, ACTpol and CMB-S4,
as relatively small changes in the observable--mass scaling relations (within
theoretical uncertainties) have a large impact on the predicted number of
high-redshift clusters and hence on our ability to constrain cosmology using
cluster abundances. In addition, we find that the intrinsic scatter of the
relations, which agrees well with most observational constraints, increases at
lower redshifts and for lower mass systems. This calls for a more complex
parametrization than adopted in current observational studies to be able to
accurately account for selection biases.
