An alternative validation strategy for the Planck cluster catalog and
  $y$-distortion maps
  We present an all sky map of the $y$-type distortion calculated from the full
mission Planck HFI (High Frequency Instrument) data using the recently proposed
approach to component separation based on parametric model fitting and model
selection. This simple model selection approach allows us to distinguish
between carbon monoxide (CO) line emission and $y$-type distortion, something
that is not possible using the internal linear combination based methods. We
create a mask to cover the regions of significant CO emission relying on the
information in the $\chi^2$ map obtained when fitting for the $y$-distortion
and CO emission to the lowest four HFI channels. We revisit the second Planck
cluster catalog and try to quantify the quality of the cluster candidates in an
approach that is similar in spirit to Aghanim et al. (2014). We find that at
least $93\%$ of the clusters in the cosmology sample are free of CO
contamination. We also find that $59\%$ of unconfirmed candidates may have
significant contamination from molecular clouds. We agree with Planck
collaboration (2015) for the worst offenders. We suggest an alternative
validation strategy of measuring and subtracting the CO emission from the
Planck cluster candidates using radio telescopes thus improving the reliability
of the catalog. Our CO mask and annotations to the Planck cluster catalog
identifying cluster candidates with possible CO contamination are made publicly
available.
