Noema formIng Cluster survEy (NICE): Discovery of a starbursting galaxy group with a radio-luminous core at <i>z</i> = 3.95
Luwenjia Zhou, Tao Wang, E. Daddi, R. T. Coogan, Hanwen Sun, Ke Xu, V. Arumugam, Shuowen Jin, Daizhong Liu, Shiying Lu, Nikolaj B. Sillassen, Yulei Wang, Yong Shi, Zhoujian Zhang, Qinghua Tan, Qiusheng Gu, D. Elbaz, Aurélien Le Bail, B. Magnelli, Carlos Gómez-Guijarro, Chiara D’Eugenio, G. Magdis, Francesco Valentino, Zhiyuan Ji, R. Gobat, I. Delvecchio, Mengyuan Xiao, V. Strazzullo, A. Finoguenov, Eva Schinnerer, R. Michael Rich, J. S. Huang, Y. Sophia Dai, Yang Chen, F. Gao, Tao Yang, Qi Hao
Abstract
The study of distant galaxy groups and clusters at the peak epoch of star formation is limited by the lack of a statistically and homogeneously selected and spectroscopically confirmed sample. Recent discoveries of concentrated starburst activities in cluster cores have opened a new window to hunt for these structures based on their integrated IR luminosities. Here, we carry out a large NOEMA (NOrthern Extended Millimeter Array) program targeting a statistical sample of infrared-luminous sources associated with overdensities of massive galaxies at z > 2, the Noema formIng Cluster survEy (NICE). We present the first result from the ongoing NICE survey, a compact group at z = 3.95 in the Lockman Hole field (LH-SBC3), confirmed via four massive ( M ⋆ ≳ 10 10.5 M ⊙ ) galaxies detected in the CO(4–3) and [CI](1–0) lines. The four CO-detected members of LH-SBC3 are distributed over a 180 kpc physical scale and the entire structure has an estimated halo mass of ∼10 13 M ⊙ and total star formation rate of ∼4000 M ⊙ yr −1 . In addition, the most massive galaxy hosts a radio-loud active galactic nucleus with L 1.4 GHz, rest = 3.0 × 10 25 W Hz −1 . The discovery of LH-SBC3 demonstrates the feasibility of our method to efficiently identify high- z compact groups or cluster cores undergoing formation. The existence of these starbursting cluster cores up to z ∼ 4 provides critical insights into the mass assembly history of the central massive galaxies in clusters.