# SCUBA-2 follow-up of Herschel-SPIRE observed Planck overdensities

## TL;DR

This study uses SCUBA-2 and Herschel-SPIRE data to analyze Planck overdensities, revealing high-redshift starburst galaxies and gravitational lenses, with significant implications for understanding early universe star formation.

## Contribution

It provides the first detailed characterization of Planck overdensity fields using SCUBA-2, identifying strong lenses and proto-cluster candidates with estimated redshifts and luminosities.

## Key findings

- Confirmed 10 strong gravitational lenses.
- Most sources have star-formation rates around 1000 solar masses per year.
- Detected sources account for only 5% of Planck flux, indicating many fainter sources.

## Abstract

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.