Cosmic fireflies

Galaxies glow like fireflies in this spectacular NASA/ESA Hubble Space Telescope image! This flickering swarm of cosmic fireflies is a rich cluster of galaxies called Abell 2163. Abell 2163 is a member of the Abell catalogue , an all-sky catalogue of over 4000 galaxy clusters . It is particularly well-studied because the material sitting at its core (its intracluster medium ) exhibits exceptional properties, including a large and bright radio halo and extraordinarily high temperatures and X-ray luminosities . It is the hottest cluster in the catalogue! Observing massive clusters like Abell 2163 can contribute to the study of dark matter , and provide a new perspective on the distant Universe via phenomena such as gravitational lensing .

This image was taken by Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3 , partially for an extensive observing programme called RELICS . The programme is imaging 41 massive galaxy clusters to find the brightest distant galaxies, which will be studied in more detail using both current telescopes and the future NASA/ESA/CSA James Webb Space Telescope (JWST).