Supermassive black hole in our Galaxy’s centre turned mysteriously bright


Sagittarius A* (Sgr A*), which is a supermassive black hole at the heart of our galaxy Milky Way, suddenly glowed brighter than its normal state becoming 75 times more luminescent before going back to its normal state. Nearly 26,000 light years from Earth, Sagittarius A* - or Sgr A* - is typically fairly restrained as supermassive black holes go, but this past summer that has all been flipped. The black hole is always variable, but this was the brightest we've seen in the infrared so far.

Scientists say the entire light show lasted just 2.5 hours, speculating that the effect may be a delayed reaction to the close passage of star S0-2 in 2018, or the G2 dust cloud, which approached the black hole in 2014. There's been a ton of speculation regarding what the heck caused the burst in infrared light, but it seems like a lot of astronomers, including those that discovered the flash, think that the supermassive black hole may be... feeding.

S0-2 has been spotted a mere 17 light-hours away from the center as recently as past year, and it's possible that the star's close relationship with the black hole has led to an increase in gas being swallowed up by it, which may have led to a burst of radiation visible using infrared. It was probably even brighter before we started observing that night! But no one was aware that anything was drawing close enough to be swallowed by the black hole. They hope to find out whether the black hole is more active than usual, or if something else accounts for the unprecedented brightness. If it was a gas cloud, this proximity should have torn it to shreds, and parts of it devoured by the black hole - yet nothing happened.

Black holes are objects so dense that beyond a zone called the event horizon, their gravitational field warps space to the point that light can't escape.

But - have a look at the timelapse again.

In the study, they suggest that the statistical models for the black hole and its variability need to be updated to track these changes in luminosity. That's S0-2, a star on a long, looping, 16-year elliptical orbit around Sgr A*. It made its closest approach yet past year, coming within 17 light hours of the event horizon.

Do told Science Alert, 'One of the possibilities, is that the star S0-2, when it passed close to the black hole previous year, changed the way gas flows into the black hole, and so more gas is falling on it, leading it to become more variable'.

Currently, scientists are gathering as much information as they can. However four other telescopes - including Spitzer, Swift, Chanrdra, and ALMA - have been making observations over the summer, with their data still to be released.

"I'm eagerly awaiting their results", Do said. The study is now available on a preprint website arXiv.