Astronomers Get as Close as They Can to Seeing the Black Hole at the Heart of the Milky Way

"It’s mind-boggling to actually witness material orbiting a massive black hole at 30% of the speed of light. GRAVITY’s tremendous sensitivity has allowed us to observe the accretion processes in real time in unprecedented detail."

The observations they conducted also confirmed the theory that Sag A* is indeed a supermassive black hole - otherwise known as the "massive black hole paradigm". As Genzel explained, this accomplishment is something scientists have been looking forward to for decades. "This always was one of our dream projects but we did not dare to hope that it would become possible so soon," he said.

Interestingly, this is not the first time that the GRAVITY collaboration has used the VLTI to observe the center of our galaxy. Earlier this year, the team used GRAVITY and the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) instrument to measure the movements of a star as it conducted a close fly-by with Sag A*.

As the star (S2) passed close to the extreme gravitational field of Sagittarius A*, the team measured the star's position and velocity and compared these to previous measurements. After comparing them to various theories of gravity, they were able to confirm that the star's behavior was consistent with predictions made by Einstein's Theory of General Relativity.

This was a major accomplishment, as it was the first time that General Relativity had been confirmed in such an extreme environment. As Pfuhl explained:

"We were closely monitoring S2, and of course we always keep an eye on Sagittarius A*. During our observations, we were lucky enough to notice three bright flares from around the black hole — it was a lucky coincidence!"

In the end, these groundbreaking observations were made possible thanks to a combination of international collaboration and state-of-the-art instruments. In the future, more advanced instruments - and improved methods of data-sharing - are sure to unlock even more mysteries of the Universe and help scientists understand how it came to be.

And be sure to check out this ESOcast that talks about this recent discovery, courtesy of the ESO: