National Optical Astronomy Observatory | 2016 May 25
[c][attachment=0]protocluster[1].jpg[/attachment][/c][hr][/hr]Astronomers have uncovered evidence for a vast collection of young galaxies 12 billion light years away. The newly discovered “proto-cluster” of galaxies, observed when the universe was only 1.7 billion years old (12% of its present age), is one of the most massive structures known at that distance. The discovery, made using telescopes at Kitt Peak National Observatory in Arizona and the W. M. Keck Observatory on Mauna Kea, has been reported in the Astrophysical Journal.
“The protocluster will very likely grow into a massive cluster of galaxies like the Coma cluster, which weighs more than a quadrillion suns,” said Purdue University astrophysicist Dr. Kyoung-Soo Lee, who initially spotted the protocluster and is one of the authors in this study. Clusters this massive are extremely rare: only a handful of candidates are known at such early times. The new system is the first to be confirmed using extensive spectroscopy to establish cluster membership.
The team, led by Dr. Lee (Purdue University) and Dr. Arjun Dey of the National Optical Astronomy Observatory, used the Mayall telescope on Kitt Peak to obtain very deep images of a small patch of sky, about the size of two full moons, in the constellation of Bootes. The team then used the Keck II Telescope on Mauna Kea to measure distances to faint galaxies in this patch, which revealed the large grouping. “Many of the faint galaxies in this patch lie at the same distance,” say Dr. Dey. “They are clumped together due to gravity and the evidence suggests that the cluster is in the process of forming.” ...
Spectroscopic Confirmation of a Protocluster at z=3.786 - Arjun Dey et al
- Astrophysical Journal 823(1):11 (20 May 2016) DOI: 10.3847/0004-637X/823/1/11
arXiv.org > astro-ph > arXiv:1604.08627 > 28 Apr 2016