It’s not uncommon for astronomers to find supermassive black holes at the center of massive galaxies, but it is somewhat unusual for astronomers to see them at the center of ultra-compact dwarf galaxies.
With that in mind, new evidence for the existence of a supermassive black hole at the center of Fornax UCD3 in the Fornax galaxy cluster is turning a quite a few heads in the scientific community.
Image Credit: NASA/STScI/ESO/Afanasiev et al.
An international team of astronomers claims to have made the discovery after peering at the distant galaxy cluster with the SINFONI instrument on one of the European Space Observatory’s 8.2-meter Very Large Telescopes (VLT). The findings have been published this week in the Monthly Notices of the Royal Astronomical Society.
"We have discovered a supermassive black hole in the center of Fornax UCD3. The black hole mass is 3.5 million that of the sun, similar to the central black hole in our own Milky Way," explained astronomer Anton Afanasiev, the paper’s first author.
Ultracompact dwarf galaxies stand out from the crowd because they pack a lot of matter into a relatively small stellar system. The radius of ultra-compact dwarf galaxies rarely surpasses 300 light-years, yet the amount of mass they encompass is comparable to a typical galaxy.
As you might come to expect, ultracompact galaxies contain lots of stars just like normal ones do, and this is precisely what the astronomers studied while peeking at Fornax UCD3. During their analysis, they discerned signs of velocity dispersion, an attribute of stars that reside close to supermassive black holes.
Computer models factored in the levels of velocity dispersion that were observed, and the researchers concluded that the supermassive black hole at the center of Fornax UCD3 sported a mass equivalent to 3.5 million solar masses, or 4% of the mass of the entire galaxy.
Finding a supermassive black hole at the center of an ultracompact dwarf galaxy is undoubtedly rare, but not unheard of. This research marks only the fourth known instance of these particular circumstances in modern astronomy, a mind-boggling statistic that underscores its importance.
Future studies may uncover more ultra-compact dwarf galaxies with supermassive black holes at their centers, but only time will tell.