Emergence of an Ultra-Red Ultra-Massive Galaxy Cluster Core at $z=4$

Understand

Recent simulations and observations of massive galaxy cluster evolution predict that the majority of stellar mass build up happens within cluster members by $z=2$, before cluster virialization.

• Protoclusters rich with dusty, star-forming galaxies (DSFGs) at $z>3$ are the favored candidate progenitors for these massive galaxy clusters at $z\sim0$.
• We present here the first study analyzing stellar emission along with cold dust and gas continuum emission in a spectroscopically confirmed $z=4.002$ protocluster core rich with DSFGs, the Distant Red Core (DRC).
• We combine new HST and Spitzer data with existing Gemini, Herschel, and ALMA observations to derive individual galaxy-level properties, and compare them to coeval field and other protocluster galaxies.