The black hole in the center of the Sculptor Galaxy was photographed "napping" by NASA. The black hole is believed to have been dormant within the last decade.
The Sculptor Galaxy, or NGC 253, is approximately 13 million light-years from Earth, and the new photo of the black hole at its center was taken by NASA’s Nuclear Spectroscopic Telescope Array, or NuStar. The new research was published in Astrophysical Journal. The black hole had previously been active and NuStar was able to capture it consuming nearby gas nearly a decade ago.
Speaking about the findings, Bret Lehmer, from Johns Hopkins University and NASA’s Goddard Space Flight Center, said, “Our results imply that the black hole went dormant in the past 10 years.” If the black hole becomes active Lehmer believes astronomers will be able to capture the moment using NuStar or the Chandra X-ray Observatory.
The black hole weighs more than five million times our Sun, notes NASA. NGC 253 is considered a starburst galaxy or a galaxy experiencing an extremely high level of star formation activity. The Sculptor Galaxy is also one of the closest starburst galaxies to the Milky Way, notes NASA, making it an important source of research for astronomers.
The Milky Way Galaxy and the Sculptor Galaxy both share a dormant black hole at their centers but the Milky Way is not considered a starburst galaxy. What’s unusual about the Sculptor Galaxy’s black hole is that it is dormant despite the wealth of fuel surrounding it.
Black holes use surrounding matter that’s being pulled to form new stars as fuel. Once this fuel source is spent, black holes become dormant. In the case of the Sculptor Galaxy’s black hole, there are plenty of new stars being formed around it, yet it became dormant within the last 10 years.
The study’s co-author, Ann Hornschemeier, from NASA’s Goddard Space Flight Center, said, “NGC 253 is somewhat unusual because the giant black hole is asleep in the midst of tremendous star-forming activity all around it.” According to NASA, it is believed all galaxies contain a massive black hole at their center, and some of the more massive black holes grow alongside the galaxy’s star formation activity. In theory, Sculptor Galaxy’s black hole should be active and consuming the nearby matter.
It is unclear why the black hole is dormant while it's surrounded by plenty of star formation activity, but the researchers believe the NuStar and Chandra will be able to solve the mystery. One theory is that the activity captured a decade, by detecting x-ray light given off by stars as they are consumed by a black hole, may have been misidentified as black hole activity.
The astronomers observing the dormant black hole also discovered several ultraluminous X-ray sources," or ULX, seen as a blue blob near the galaxy's center. According to NASA, ULX are black holes consuming material and gas from partner stars. According to Hornschemeier, ULX may be found more frequently in areas of high star formation activity, and astronomers are only beginning to understand these types of black holes.