Emulation of baryonic effects on the matter power spectrum and
  constraints from galaxy cluster data
  Baryonic feedback effects consist of a major systematic for upcoming
weak-lensing and galaxy-clustering surveys. In this paper, we present an
emulator for the baryonic suppression of the matter power spectrum. The
emulator is based on the baryonification model, containing seven free
parameters that are connected to the gas profiles and stellar abundances in
haloes. We show that with the baryonic emulator, we can not only recover the
power spectra of hydro-dynamical simulations at sub-percent precision but also
establish a connection between the baryonic suppression of the power spectrum
and the gas and stellar fractions in haloes. This connection allows us to
predict the expected deviation from a dark-matter-only power spectrum using
measured X-ray gas fractions of galaxy groups and clusters. With these
measurements, we constrain the suppression to exceed the percent-level at k =
0.1-0.4 h/Mpc and to reach a maximum of 20-28 percent at around k = 7 h/Mpc (68
percent confidence level). As a further step, we also perform a detailed
parameter study and we present a minimum set of four baryonic parameters that
are required to recover the scale and redshift dependence observed in
hydro-dynamical simulations. The baryonic emulator can be found at
https://github.com/sambit-giri/BCemu.
