Abell 98 is a system of galaxy clusters in the early stages of a collision. Astronomers have used Chandra data to identify key structures in this system and search for some of the "normal" matter (not dark matter) missing from most observations of the local universe. Scientists have proposed that at least some of this unaccounted-for mass could be hidden in gigantic strands known as the "warm-hot intergalactic medium," or WHIM. The Chandra study has found evidence for the WHIM in Abell 98, shown here in images from Chandra and the WIYN telescope.

This tactile plate depicts a system of galaxy clusters known as Abell 98, as a physical relief map based on the intensity of X-ray data captured by Chandra and optical data from the WIYN telescope. The file for this plate can be downloaded and 3D-printed for learners to touch.

The plate of Abell 98, about 1.4 billion light years from Earth, depicts little specks — mostly galaxies. Near the top and bottom of the plate are clouds of gas, each with a cluster of galaxies at its core. The two galaxy clusters are in the early stages of a collision. Upon close inspection, a faint corridor of gas can be found bridging the space between the clusters. Scientists have proposed that this X-ray bridge between the clusters contains some of the unaccounted-for mass in the universe. Hidden in this bridge are gigantic strands, or filaments, of hot gas.