Exploring the hydrostatic mass bias in MUSIC clusters: application to
  the NIKA2 mock sample
  Clusters of galaxies are useful tools to constrain cosmological parameters,
only if their masses can be correctly inferred from observations. In
particular, X-ray and Sunyaev-Zeldovich (SZ) effect observations can be used to
derive masses within the framework of the hydrostatic equilibrium. Therefore,
it is crucial to have a good control of the possible mass biases that can be
introduced when this hypothesis is not valid. In this work, we analyzed a set
of 260 synthetic clusters from the MUSIC simulation project, at redshifts $0
\leq z \leq 0.82$. We estimate the hydrostatic mass of the MUSIC clusters from
X-ray only (temperature and density) and from X-ray and SZ (density and
pressure). Then, we compare them with the true 3D dynamical mass. The biases
are of the order of 20%. We find that using the temperature instead of the
pressure leads to a smaller bias, although the two values are compatible within
1$\sigma$. Non-thermal contributions to the total pressure support, arising
from bulk motion and turbulence of the gas, are also computed and show that
they are sufficient to account for this bias. We also present a study of the
correlation between the mass bias and the dynamical state of the clusters. A
clear correlation is shown between the relaxation state of the clusters and the
bias factor. We applied the same analysis on a subsample of 32 objects, already
selected for supporting the NIKA2 SZ Large Program.
