This image composite shows a giant galactic blob (red, figure 2) and the
three merging galaxies NASA's Spitzer Space Telescope discovered within
it (yellow, figure 3).
Blobs are intensely glowing clouds of hot hydrogen gas that envelop
faraway galaxies. They are about 10 times as large as the galaxies they
surround. Visible-light images like the one shown in figure 2, reveal the
vast extent of blobs, but don't provide much information about their host
galaxies.
Using its heat-seeking infrared eyes, Spitzer was able to see the dusty
galaxies tucked inside one well-known blob located 11 billion light-years
away. The findings reveal three monstrously bright galaxies, trillions of
times brighter than the Sun, in the process of merging together (figure 3).
Spitzer also observed three other blobs located in the same cosmic
neighborhood, all of which were found to be glaringly bright. One of
these blobs is also known to be a galactic merger, only between two
galaxies instead of three. It remains to be seen whether the final two
blobs studied also contain mergers.
The Spitzer data were acquired by its multiband imaging photometer. The
visible-light image was taken by the Blanco Telescope at the Cerro Tololo
Inter-American Observatory, Chile.
