Images of eight galaxies containing green filaments that are the last effect of ancient quasars (Image NASA, ESA, and W. Keel (University of Alabama, Tuscaloosa))

The Hubble Space Telescope photographed a series of ghosts of quasars that existed in the past. They are seen as ethereal green objects in various forms and are the last effects of ancient quasars. These phenomena are very interesting from a scientific standpoint because they can provide information about the past of those galaxies, which were once very active.

The Planck all-sky map at submillimetre wavelengths with the protoclusters indicated as black dots. The inset images showcase some of the observations made by Herschel’s SPIRE instrument (Image ESA and the Planck Collaboration/ H. Dole, D. Guéry & G. Hurier, IAS/University Paris-Sud/CNRS/CNES)

An article published in the journal “Astronomy & Astrophysics” describes the results of a research carried out by combining the observations made with ESA’s Herschel and Planck space telescopes. The purpose was to find protoclusters, the precursors of today’s galaxy clusters seen in the distant past when the universe was only three billion years. This will help to understand how these huge groups of tens, hundreds and even thousands of galaxies formed and evolved.