Exploiting NIKA2/XMM-Newton imaging synergy for intermediate mass,
  high-$z$ galaxy clusters within the NIKA2 SZ Large Program
  High-resolution mapping of the intra-cluster medium (ICM) up to high redshift
and down to low masses is crucial to derive accurate mass estimates of the
galaxy cluster and to understand the systematic effects affecting cosmological
studies based on galaxy clusters. We present a spatially-resolved
Sunyaev-Zel'dovich (SZ)/X-ray analysis of ACT-CL J0215.4+0030, a high redshift
($z=0.865$) galaxy cluster of intermediate mass
($M_{500}\simeq3.5\times10^{14}\;\mathrm{M_\odot}$) observed as part of the
ongoing NIKA2 SZ Large Program, a follow up of a representative sample of
objects at $0.5 \leqslant z \leqslant 0.9$. In addition to the faintness and
small angular size induced by its mass and redshift, the cluster is
contaminated by point sources that significantly affect the SZ signal.
Therefore, this is an interesting case study for the most challenging sources
of the NIKA2 cluster sample. We present the NIKA2 observations of this cluster
and the resulting data. We reconstruct the ICM pressure profile by performing a
joint analysis of the SZ signal and of the point sources in the NIKA2 150 GHz
map. We obtain high-quality estimates of the ICM thermodynamical properties
with NIKA2. We compare the pressure profile extracted from the NIKA2 map to the
pressure profile obtained from X-ray data only by deprojecting XMM-Newton
observations of the cluster. We combine the NIKA2 pressure profile with the
X-ray deprojected density to extract detailed information on the ICM. The
radial distribution of its thermodynamic properties indicate that the cluster
has a disturbed core. The hydrostatic mass of the cluster is to be compatible
with estimations from SZ and X-rays scaling relations. We conclude that the
NIKA2 SZ large program can deliver quality information on the thermodynamics of
the ICM even for one of its faintest clusters, after a careful treatment of the
contamination by point sources.
