Supermassive black hole found in small, distant galaxy

Astronomers have discovered a supermassive black hole at the center of a tiny galaxy, giving new insight into the odd formations.
By Joseph Scalise | Aug 16, 2018
For the first time in history astronomers have discovered a supermassive black hole at the center of a tiny galaxy, a new study published in the Monthly Notices of the Royal Astronomical Society reports.

The distant galaxy -- called Fornax UCD3 -- is a rare system known as a ultracompact dwarf. The regions are only populated by old stars, which is one of the many features that make them unique.

"UCDs are rather compact stellar systems with typical radii of about 100 parsecs (around 326 light-years), while their masses are up to 100 million solar masses," lead author Anton Afanasiev, a researcher at Moscow State University, told Newsweek. "As a result their stars exist 'densely packed,' with interstellar distances way shorter than in our galaxy."

In contrast, the Milky Way's radius is 50,000 light years and its mass is estimated to be hundreds of billions times that of the sun.

However, while Fornax is small, an international team of scientists found that the black hole at its center has a mass roughly equivalent to 3.5 million times the sun. That is extremely close to the black hole at the heart of the Milky Way, known as Sagittarius A.

The hole is the fourth to ever be found in an ultracompact dwarf, and it makes up roughly 4 percent of the galaxy's total mass. That is much more than the .3 percent black holes account for in normal galaxies.

The team found the supermassive black hole by using data collected by an infrared-detecting instrument known as SINFONI.

The finding is important because it supports the hypothesis that ultracompact dwarfs form when an average-sized galaxy passes a larger and more massive one during its evolution, a process that causes the region to lose most of its stars to tidal forces.

Supermassive black holes are found at the center of every galaxy. Though researchers are not sure if ultracompact dwarfs are galaxies, this could help show that they are. Either way, the team in the new research believes they all have a supermassive black hole at their center.

"Speaking of supermassive black holes, there is a research proving a non-detection of massive black holes in the centre of two UCDs," added Afanasiev. "However we assume that the majority of UCDs still should have a central supermassive black hole, as it is dictated by what we believe is their main formation mechanism."

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