The Most Massive Objects in the Modern Universe –Primordial Relics of the Cosmic Microwave Background

Merging Galaxies of the Early Universe


“In Big Bang cosmology, the cosmic microwave background (CMB) is in some sense a map of fluctuations thought to be linked to variations in the matter density of the primordial expansion of the universe,” explains Harvard astronomer Matthew Ashby in an email to The Daily Galaxy about the formation of massive galaxy clusters from the cosmic web of filaments, nodes, and voids, with the nodes being clusters of galaxies. “Their amplitude is very small. But, because they trace fluctuations in the primordial density of matter, they will grow over cosmic time through the action of gravity.  And for that reason, massive coherent structures such as galaxy cluster SPT2349-56, the most massive objects in the modern Universe, are of great interest, being among the very first to form (that is, collapse) out of those ancient fluctuations.