NASA Watches Black Hole Nap After Snacking on Gas in Starburst Galaxy

Almost a decade ago, NASA's Chandra X-ray Observatory watched as a black hole snacked on gas in the middle of a nearby galaxy. Now, it seems that after having this massive midnight snack, the black hole has promptly fallen asleep.

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), which sees higher-energy X-ray light, has shown new signs of this slumbering black hole. About five million times the mass of our sun, the black hole lies at the center of the Sculptor galaxy, also known as NGC 253. This galaxy gives birth to new stars at a phenomenal rate, earning it the name of a starburst galaxy. At 13 million light-years away, it's one of the closest starburst galaxies to the Milky Way.

Chandra first discovered the hungry black hole in 2003. Material spiraled into the mouth of the black hole, heating up to tens of millions of degrees. This superheated material glowed in X-ray light, which allowed Chandra to witness the black hole in the first place.

Yet that all changed in 2012. That's when both Chandra and NuSTAR imaged the same region simultaneously. The NuSTAR observations in particular allowed scientists to see that the black hole wasn't accreting material, despite being in such an active starburst galaxy.

"Black hole growth and star formation often go hand-in-hand in distant galaxies," said Daniel Stern, co-author of the new study, in a news release. "It's a bit surprising as to what's going on here, but we've got two powerful complementary X-ray telescopes on the case."

Although it seems like the black hole has fallen asleep, there's another possibility for its sudden inactivity. It may not have even been "awake" ten years ago. It's possible that Chandra observed a different source of X-rays, which means that scientists are now interested in tracking down the truth.

"The combination of coordinated Chandra and NuSTAR observations is extremely powerful for answering questions like this," said Lou Kaluzienski, NuStar program scientists, in a news release. "Now, we can get all sides of the story."

Currently, scientists are focused on further investigating this slumbering black hole.