Detection and characterisation of the first Planck high-z candidates

Abstract

With its unprecedented ability to scrutinise the sub-millimetre (sub-mm) to centimetre full sky, the Planck satellite is uniquely suited to search for the progenitors of clusters of galaxies. The forming massive halos at z ≳1-2 are expected to host massive galaxies with high star formation rates. Clustered in the growing potential well that is being established, these galaxies are within Planck's reach via their sub-mm emission. We have applied a new colour-based method combining Planck and IRAS data to detect the rarest and brightest sub-mm cold sources on the sky. In this work, we describe the method and present the first confirmations of our high-z candidates, particularly focusing on 17p732, a newly discovered high-z (proto)cluster candidate at z≃1.7 for which we carried a multi-wavelength follow-up.