SCUBA-2 follow-up of Herschel-SPIRE observed Planck overdensities
  We present SCUBA-2 follow-up of 61 candidate high-redshift Planck sources. Of
these, 10 are confirmed strong gravitational lenses and comprise some of the
brightest such submm sources on the observed sky, while 51 are candidate
proto-cluster fields undergoing massive starburst events. With the accompanying
Herschel-SPIRE observations and assuming an empirical dust temperature prior of
$34^{+13}_{-9}$ K, we provide photometric redshift and far-IR luminosity
estimates for 172 SCUBA-2-selected sources within these Planck overdensity
fields. The redshift distribution of the sources peak between a redshift of 2
and 4, with one third of the sources having $S_{500}$/$S_{350} > 1$. For the
majority of the sources, we find far-IR luminosities of approximately
$10^{13}\,\mathrm{L}_\odot$, corresponding to star-formation rates of around
$1000$ M$_\odot \mathrm{yr}^{-1}$. For $S_{850}>8$ mJy sources, we show that
there is up to an order of magnitude increase in star-formation rate density
and an increase in uncorrected number counts of $6$ for $S_{850}>8$ mJy when
compared to typical cosmological survey fields. The sources detected with
SCUBA-2 account for only approximately $5$ per cent of the Planck flux at 353
GHz, and thus many more fainter sources are expected in these fields.
