A Lyman-α protocluster at redshift 6.9

Autor: Junxian Wang, Santosh Harish, Lucia A. Perez, Alistair R. Walker, Xu Kong, Xianzhong Zheng, Ali Ahmad Khostovan, Leopoldo Infante, Isak Wold, Chunyan Jiang, Alicia Coughlin, Jorge González-López, Weida Hu, John Pharo, Huan Yang, Zhen-Ya Zheng, Gonzalo Prieto, L. Felipe Barrientos, James E. Rhoads, Gaspar Galaz, Wenyong Kang, Pascale Hibon, Francisco Valdes, Sangeeta Malhotra
Rok vydání: 2021
Předmět:
Zdroj: Nature Astronomy. 5:485-490
ISSN: 2397-3366
Popis: Protoclusters, the progenitors of the most massive structures in the Universe, have been identified at redshifts of up to 6.6. Besides exploring early structure formation, searching for protoclusters at even higher redshifts is particularly useful to probe the reionization. Here we report the discovery of the protocluster LAGER-z7OD1 at a redshift of 6.93, when the Universe was only 770 million years old and could be experiencing rapid evolution of the neutral hydrogen fraction in the intergalactic medium. The protocluster is identified by an overdensity of 6 times the average galaxy density, and with 21 narrowband selected Lyman-$\alpha$ galaxies, among which 16 have been spectroscopically confirmed. At redshifts similar to or above this record, smaller protogroups with fewer members have been reported. LAGER-z7OD1 shows an elongated shape and consists of two subprotoclusters, which would have merged into one massive cluster with a present-day mass of $3.7 \times 10^{15}$ solar masses. The total volume of the ionized bubbles generated by its member galaxies is found to be comparable to the volume of the protocluster itself, indicating that we are witnessing the merging of the individual bubbles and that the intergalactic medium within the protocluster is almost fully ionized. LAGER-z7OD1 thus provides a unique natural laboratory to investigate the reionization process.
Comment: 9 pages, 5 figures, and 1 table. Accepted by Nature Astronomy
Databáze: OpenAIRE
Externí odkaz: