A multi-instrument non-parametric reconstruction of the electron
  pressure profile in the galaxy cluster CLJ1226.9+3332
  Context: In the past decade, sensitive, resolved Sunyaev-Zel'dovich (SZ)
studies of galaxy clusters have become common. Whereas many previous SZ studies
have parameterized the pressure profiles of galaxy clusters, non-parametric
reconstructions will provide insights into the thermodynamic state of the
intracluster medium (ICM). Aims: We seek to recover the non-parametric pressure
profiles of the high redshift ($z=0.89$) galaxy cluster CLJ 1226.9+3332 as
inferred from SZ data from the MUSTANG, NIKA, Bolocam, and Planck instruments,
which all probe different angular scales. Methods: Our non-parametric algorithm
makes use of logarithmic interpolation, which under the assumption of
ellipsoidal symmetry is analytically integrable. For MUSTANG, NIKA, and Bolocam
we derive a non-parametric pressure profile independently and find good
agreement among the instruments. In particular, we find that the non-parametric
profiles are consistent with a fitted gNFW profile. Given the ability of Planck
to constrain the total signal, we include a prior on the integrated Compton Y
parameter as determined by Planck. Results: For a given instrument, constraints
on the pressure profile diminish rapidly beyond the field of view. The overlap
in spatial scales probed by these four datasets is therefore critical in
checking for consistency between instruments. By using multiple instruments,
our analysis of CLJ 1226.9+3332 covers a large radial range, from the central
regions to the cluster outskirts: $0.05 R_{500} < r < 1.1 R_{500}$. This is a
wider range of spatial scales than is typical recovered by SZ instruments.
Similar analyses will be possible with the new generation of SZ instruments
such as NIKA2 and MUSTANG2.
