Article image

Spin of a new black hole is unlocking galactic mysteries

For years, the supermassive black hole at the heart of our Milky Way galaxy, Sagittarius A* (Sgr A*), has captivated scientists with its enigmatic presence. Now, scientists stand awestruck at the black hole’s breathtaking spin, a revelation that unlocks a new chapter in our understanding of black holes.

“Our work may help settle the question of how fast our galaxy’s supermassive black hole is spinning,” said Dr. Ruth Daly, a professor at Penn State. “Our results indicate that Sgr A* is spinning very rapidly, which is interesting and has far-reaching implications.”

Measuring black hole spin

Analyzing the black hole, the scientists studied data from X-ray and radio telescopes to understand how fastSgr A* spins. They used a special method called the outflow method to focus on the “wind” of particles flowing out from the black hole. 

By measuring the energy and direction of this wind, they could estimate how fast the black hole is spinning. This is important because it helps us understand how black holes form and grow, and how they affect their surroundings.

Key values

Scientists calculated two key values to measure the spin:

  • Spin function: This reveals how the black hole’s spin influences its ability to launch powerful jets of material.
  • Dimensionless spin: This acts like a “speedometer” for the black hole’s spin, comparing its rotation to its size.

Shape and black hole spin speed

Researchers discovered that Sgr A* is spinning at an extremely high rate, approximately 60% of its theoretical maximum speed. This spin is crucial, as it’s a black hole’s fundamental property alongside its mass. 

Additionally, the spin doesn’t just sit there quietly. Its immense gravitational pull and rapid pace literally bend and twist the fabric of spacetime around it, warping it into a shape resembling a football.

Einstein’s theory of general relativity predicted this relativistic effect – the spinning black hole “drags” spacetime along with it.

Think of spacetime as a flexible sheet. A giant, rapidly spinning object like Sgr A* wouldn’t just rest on it; it would twist and distort the sheet under its influence. And this distortion isn’t even; it’s shaped like a football because of the specific way the black hole’s rotation affects spacetime.

Consequences of the spinning

The warped spacetime and fast spin of Sgr A* have several consequences for its surrounding environment. The spin affects how matter falls into the black hole. Instead of a straight plunge, the material gets “swirled” due to the spin, influencing its trajectory and rate of infall.

The rapid spin also fuels powerful jets of material shooting out from the black hole. These jets are not random but influenced by the spin, potentially affecting their direction and intensity.

Both the warped spacetime and energetic jets affect how Sgr A* interacts with nearby stars and gas. The black hole’s spin dictates the movement of these celestial objects, impacting their potential interactions.

Future activity of Sgr A* 

Currently, the Sgr A* is in a relatively inactive state. This means it’s interacting minimally with nearby matter, unlike its usual behavior of swallowing gas and dust and ejecting powerful jets.

Sgr A*’s current “outflows” – streams of matter and energy – are weak and diffuse, suggesting limited fuel available near the black hole. However, this state could change dramatically if more material gets close. Events like a star wandering too close or gas clouds drifting nearby could provide fresh “food” for the black hole.

“This work, however, shows that this could change if the amount of material in the vicinity of Sgr A* increases,” said Professor Daly. Increased material would allow Sgr A*’s spin to generate stronger, more focused outflows. The black hole’s rotation efficiently transfers energy to incoming matter, accelerating it to high speeds.

Broader implications of black hole spin

When it’s active, Sgr A*’s spin can energize the material it pulls in, creating powerful and focused jets of energy and matter. 

“A spinning black hole is like a rocket on the launch pad,” said Biny Sebastian, a co-author of the study from the University of Manitoba. “Once material gets close enough, it’s like someone has fueled the rocket and hit the ‘launch’ button.”

These jets can travel vast distances and potentially disrupt gas clouds within the galaxy, impacting star formation.

Significance and future study

The properties and behavior of supermassive black holes reveal how black holes interact with their surroundings, influenced by their spin. This helps us understand how they form, grow, and behave across cosmic time.

Moreover, studying black hole spins lets us test theories of gravity, especially general relativity, in extreme environments where gravity is incredibly strong.

By analyzing black hole spins, we can understand how jets and outflows are created, which are crucial for regulating star formation and galaxy growth.

But the story doesn’t end there. Each new spin measurement could unlock even deeper mysteries, leading us closer to understanding the very fabric of the universe. 

The study is published in the journal Monthly Notices of the Royal Astronomical Society.


Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.


Check us out on EarthSnap, a free app brought to you by Eric Ralls and


News coming your way
The biggest news about our planet delivered to you each day