The Clusters Hiding in Plain Sight (CHiPS) survey: A first discovery of
  a massive nearby cluster around PKS1353-341
  We introduce the first result of the Clusters Hiding in Plain Sight (CHiPS)
survey, which aims to discover new, nearby, and massive galaxy clusters that
were incorrectly identified as isolated point sources in the ROSAT All-Sky
Survey. We present a Chandra X-ray observation of our first newly discovered
low-redshift (z = 0.223) galaxy cluster with a central X-ray bright point
source, PKS1353-341. After removing the point source contribution to the
cluster core (L_nuc ~ 1.8x10^44 erg/s), we determine various properties of the
cluster. The presence of a relaxed X-ray morphology, a central temperature
drop, and a central cooling time around 400 Myr indicates that it is a strong
cool-core cluster. The central galaxy appears to be forming stars at the rate
of 6.2+\-3.6 Msun/yr, corresponding to ~1% of the classical cooling prediction.
The supermassive black hole in the central galaxy appear to be accreting at
~0.1% of the Eddington rate with a total power output of ~5x10^45 erg/s, split
nearly equally between radiative and mechanical power. We see weak evidence of
localized excess entropy at a radius of 200 kpc which, if true, could imply a
recent (~180 Myr) energetic outburst in the core that has risen buoyantly to a
larger radius. Comparing the cluster's bulk properties with those of other
known clusters (e.g., the total mass M_500 is 6.9(+4.3)(-2.6)x10^14 Msun, and
the bolometric X-ray luminosity L_X is 7x10^44 erg/s), we show that this
cluster, which is massive enough that it was detected (but not confirmed) by
the Planck survey, is also sufficiently luminous that it would have been
identified as a cluster in the ROSAT All-sky Survey if it did not have such a
bright central point source. This discovery demonstrates the potential of the
CHiPS survey to find massive nearby clusters with extreme central properties
that may have been missed or misidentified by previous surveys.
