@article{83331b15570e4c4eac4526d0d9bab8b2,
title = "Starbursts with suppressed velocity dispersion revealed in a forming cluster at z = 2.51",
abstract = "One of the most prominent features of galaxy clusters is the presence of a dominant population of massive ellipticals in their cores. Stellar archaeology suggests that these gigantic beasts assembled most of their stars in the early Universe via starbursts. However, the role of dense environments and their detailed physical mechanisms in triggering starburst activities remain unknown. Here we report spatially resolved Atacama Large Millimeter/submillimeter Array (ALMA) observations of the CO J = 3 - 2 emission line, with a resolution of about 2.5 kpc, toward a forming galaxy cluster core with starburst galaxies at z = 2:51. In contrast to starburst galaxies in the field often associated with galaxy mergers or highly turbulent gaseous disks, our observations show that the two starbursts in the cluster exhibit dynamically cold (rotation-dominated) gas-rich disks. Their gas disks have extremely low velocity dispersion (0 ∼ 20-30 km s-1), which is three times lower than their field counterparts at similar redshifts. The high gas fraction and suppressed velocity dispersion yield gravitationally unstable gas disks, which enables highly efficient star formation. The suppressed velocity dispersion, likely induced by the accretion of corotating and coplanar cold gas, might serve as an essential avenue to trigger starbursts in massive halos at high redshifts.",
keywords = "Galaxies: clusters: general, Galaxies: evolution, Galaxies: formation, Galaxies: high-redshift, Galaxies: ISM",
author = "Xiao, {M. Y.} and T. Wang and D. Elbaz and D. Iono and X. Lu and Bing, {L. J.} and E. Daddi and B. Magnelli and C. G{\'o}mez-Guijarro and F. Bournaud and Gu, {Q. S.} and S. Jin and F. Valentino and A. Zanella and R. Gobat and S. Martin and G. Brammer and K. Kohno and C. Schreiber and L. Ciesla and Yu, {X. L.} and K. Okumura",
note = "Funding Information: Acknowledgements. We are very grateful to the anonymous referee for instructive comments, which helped to improve the overall quality and strengthened the analyses of this work. We thank Ken-ichi Tadaki and Nicolas Bouch{\'e} for the helpful discussion of the molecular gas kinematics with GalPAK3D; Yong Shi, Alain Omont, Susan Kassin, Annagrazia Puglisi, Daizhong Liu, and Boris Sindhu Kalita for valuable discussions and suggestions that improved this paper. This paper makes use of the following ALMA data: ADS/JAO.ALMA #2016.1.01155.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), NSC, ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. This work is supported by the National Key Research and Development Program of China (No. 2017YFA0402703), and by the National Natural Science Foundation of China (Key Project No. 11733002, Project No. 12173017, and Project No. 12141301). This work is also supported by the Programme National Cosmology et Galaxies (PNCG) of CNRS/INSU with INP and IN2P3, co-funded by CEA and CNES. M.-Y. X. acknowledges the support by China Scholarship Council (CSC). T.W. and K. K. acknowledges the support by NAOJ ALMA Scientific Research Grant Number 2017-06B. D. I. acknowledges the support by JSPS KAKENHI Grant Number JP21H01133. Publisher Copyright: {\textcopyright} 2022 EDP Sciences. All rights reserved.",
year = "2022",
month = aug,
day = "1",
doi = "10.1051/0004-6361/202142843",
language = "English",
volume = "664",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
}