Using ALMA to resolve the nature of the early star-forming large-scale structure PLCK G073.4-57.5

Understand

Galaxy clusters at high redshift are key targets for understanding matter assembly in the early Universe, yet they are challenging to locate.

• A sample of >2000 high-z candidate structures has been found using Planck's all-sky submm maps, and a sub-set of 234 have been followed up with Herschel-SPIRE, which showed that the emission can be attributed to large overdensities of dusty star-forming galaxies.
• In order to resolve and characterise the individual galaxies we targeted the eight brightest SPIRE sources in the centre of the Planck peak PLCK G073.4-57.5 using ALMA at 1.3 mm, and complemented these observations with data from IRAC, WIRCam J,K, and SCUBA-2.
• We detected a total of 18 millimetre galaxies brighter than 0.3 mJy in 2.4 arcmin^2.