February 6, 2008—Though this "fossil galaxy" appears to be living out its days in cosmic isolation, scientists have found that it is actually ensconced in an enormous halo of dark matter.
The mysterious substance envelops NGC 1132 in an amount typically found in groups of tens or even hundreds of galaxies—a "cosmic oddity," Michael West of the European Organisation for Astronomical Research in the Southern Hemisphere said in an email.
In this new image released by the NASA/ESA Hubble Space Telescope, NGC 1132 is seen as a resplendent oval body with thousands of globe-shaped clusters swarming around it like bees around a hive.
The galaxy also casts a strong x-ray glow over a region ten times larger than the 120,000 light-year radius seen in visible light.
Researchers suspect NGC 1132 is the ancient remains of a gigantic multi-galactic pile-up, in which a large cannibal galaxy "that would make Hannibal Lecter proud" swallowed its nearby kin, West told National Geographic News.
"NGC 1132 and other similar fossil groups appear to the most extreme examples of galaxy cannibalism, ravenous systems that don't stop until they've eaten all their neighbors," West said.
The clusters surrounding NGC 1132 may be the sole remnants of galaxies that were eaten by the cannibal.
"By studying the globular clusters surrounding NGC 1132 today, we hope to piece together information about the number and properties of the different galaxies that once shared this region of the universe."
Another theory is that the galaxy is a rare object that formed when moderate-size galaxies were physically impossible, and so only one big galaxy coalesced.
NGC 1132 is located about 320 million light-years away in the constellation of Eridanus, named after a river in Greek mythology.