Extremely massive galaxy proto-supercluster smashes distance record

An international team of astronomers has discovered the most distant progenitor to a galaxy supercluster ever, smashing the distance record. This groundbreaking discovery supports existing theories of how galaxy clusters evolve and reveals their connection to the larger cosmic web. The study, published in The Astrophysical Journal, primarily relies on data from the ODIN survey conducted with the Dark Energy Camera on the NSF Víctor M. Blanco 4-meter Telescope in Chile.

Galaxy clusters, the most massive gravitationally bound structures in the universe, are formed when hundreds to thousands of galaxies merge and are held together by dark matter. Scientists study protoclusters, enormous loosely bound collections of galaxies in the process of merging, to understand how modern galaxy clusters grew and evolved over time.

By focusing on very distant protoclusters, researchers can gain insights into the growth of massive structures in the universe and their influence on the evolution of galaxies.

The study, led by graduate student Vandana Ramakrishnan at Purdue University, utilized data from the ODIN survey. The DECam, a 570-megapixel camera, captured deep images of a large Southern Hemisphere sky area over 100 nights in the past three years. Identifying 150 distant protoclusters, the team honed in on two clusters, COSMOS-z3.1-A and COSMOS-z3.1-C, exhibiting an unusually high concentration of galaxies.

To understand the 3D structure of these clusters, the team used spectrographs, which measure light properties to determine distances and positions in three dimensions. They employed the Dark Energy Spectroscopic Instrument, Gemini Multi-Object Spectrograph, and Keck II telescope to acquire spectra of these structures. The study produced detailed 3D maps of the protoclusters, revealing their clumpy and irregular nature and their location at the intersections of multiple cosmic web filaments.

The maps also showed that these ancient protoclusters are extremely rare, with only one expected for every 10,000 galaxy clusters.

With a mass 5,000 times that of the Milky Way galaxy, COSMOS-z3.1-A is the earliest, most distant proto-supercluster ever found, predating our local universe by 2.1 billion years. This discovery challenges current models of structure formation and suggests that the observed clumpy substructure in the 3D maps is evidence of the bottom-up growth of large-scale cosmic structures.

The ODIN survey's wide area and depth are expected to uncover more massive cosmic structures in the distant universe, helping scientists better understand the evolution of galaxies and the universe.