Emergence of an Ultrared, Ultramassive Galaxy Cluster Core at z = 4

Long, Arianna S.; Cooray, Asantha; Ma, Jingzhe; Casey, Caitlin M.; Wardlow, Julie L.; Nayyeri, Hooshang; Ivison, R. J.; Farrah, Duncan; Dannerbauer, Helmut
Bibliographical reference

The Astrophysical Journal

Advertised on:
8
2020
Number of authors
9
IAC number of authors
1
Citations
34
Refereed citations
28
Description
Recent simulations and observations of massive galaxy cluster evolution predict that the majority of stellar mass buildup 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 ∼ 0. 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 Hubble Space Telescope and Spitzer data with existing Gemini, Herschel, and Atacama Large Millimeter/submillimeter Array observations to derive individual galaxy-level properties and compare them to coeval field and other protocluster galaxies. All of the protocluster members are massive (>1010 M☉), but not significantly more so than their coeval field counterparts. Within uncertainty, all are nearly indistinguishable from galaxies on the star-forming versus stellar mass main-sequence relationship and the star formation efficiency plane. Assuming no future major influx of fresh gas, we estimate that these gaseous DSFGs will deplete their gas reservoirs in ∼300 Myr, becoming the massive quiescent ellipticals dominating cluster cores by z ∼ 3. Using various methodologies, we derive a total z = 4 halo mass of ∼1014 M☉ and estimate that the DRC will evolve to become an ultramassive cluster core of mass ≳1015 M☉ by z = 0.
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