Researchers describe one of the most massive large-scale structures in the universe
https://phys.org/news/2017-07-massive-large-scale-universe.html
A team of astronomers from the Inter University Centre for Astronomy & Astrophysics (IUCAA), and Indian Institute of Science Education and Research (IISER),
both in Pune, India, and members of two other Indian universities, have identified a previously unknown, extremely large supercluster of galaxies located in
the direction of constellation Pisces. This is one of the largest known structures in the nearby Universe, and is at a distance of 4,000 million (400 crore)
light-years away from us.
This novel discovery is being published in the latest issue of The Astrophysical Journal, the premier research journal of the American Astronomical Society.
Large-scale structures in the Universe are found to be hierarchically assembled, with galaxies, together with associated gas, and dark matter, being clumped
in clusters, which are organized with other clusters, smaller groups, filaments, sheets and large empty regions ("voids") in a pattern called the "Cosmic web"
which spans the observable Universe.
Superclusters are the largest coherent structures in the Cosmic Web. A Supercluster is a chain of galaxies and galaxy clusters, bound by gravity, often
stretching to several hundred times the size of clusters of galaxies, consisting of tens of thousands of galaxies. This newly-discovered 'Saraswati'
supercluster, for instance, extends over a scale of 600 million light-years and may contain the mass equivalent of over 20 million billion suns.