X-ray, Optical & Infrared Images of El Gordo
This galaxy cluster, which has been nicknamed "El Gordo" for the "big" or "fat" one in Spanish, is a remarkable object. Found in the distant Universe by Chandra and the Atacama Cosmology Telescope, El Gordo appears to be the most massive, the hottest, and gives off the most X-rays of any known cluster at its distance or beyond. In these images of El Gordo, X-rays are from Chandra, optical data are from the Very Large Telescope (in red, green, and blue), and infrared emission is from Spitzer (red). The comet-like shape of the X-rays, along with optical data, show that El Gordo is actually the site of a collision between two galaxy clusters, similar to the well-known Bullet Cluster.
(Credit: X-ray: NASA/CXC/Rutgers/J.Hughes et al, Optical: ESO/VLT/Pontificia Universidad. Catolica de Chile/L.Infante & SOAR (MSU/NOAO/UNC/CNPq-Brazil)/Rutgers/F.Menanteau, IR: NASA/JPL/Rutgers/F.Menanteau)

Galactic Density Map
This composite image of "El Gordo" has X-rays from Chandra (blue), optical from VLT (red, green, and blue), and infrared emission from Spitzer (red) with an extra layer in purple. These purple data show how many galaxies there are in different parts in the field of view, giving a type of galactic density map of the region.
(Credit: X-ray: NASA/CXC/Rutgers/J.Hughes et al, Optical: ESO/VLT/Pontificia Universidad. Catolica de Chile/L.Infante & SOAR (MSU/NOAO/UNC/CNPq-Brazil)/Rutgers/F.Menanteau, IR: NASA/JPL/Rutgers/F.Menanteau)