Skip to main content

The supermassive black hole at the heart of the Milky Way is getting hungrier

Rendering of a star called S0-2 orbiting the supermassive black hole at the center of the Milky Way. It did not fall in, but its close approach could be one reason for the black hole’s growing appetite. Artist's rendering by Nicolle Fuller/National Science Foundation

Last month, we learned that the supermassive black hole at the center of our galaxy was flaring, although no one was sure why. Now, astronomers from the University of California, Los Angeles (UCLA) have revealed more about what they think may be driving this unprecedented event.

Lying at the heart of the Milky Way, the Sagittarius A* or Sgr A* black hole is typically a relatively gentle giant. But when astronomers analyzed 13,000 observations of it from 133 nights since 2003, they found that on May 13 of this year the matter around the black hole glowed twice as brightly as usual. The same bright flaring was observed on two other nights this year as well. This indicates the black hole is consuming much more dust and gas on these nights than is usual.

“We have never seen anything like this in the 24 years we have studied the supermassive black hole,” Andrea Ghez, professor of physics and astronomy at UCLA and a co-author of the research, said in a statement. “It’s usually a pretty quiet, wimpy black hole on a diet. We don’t know what is driving this big feast.”

Our galaxy’s black hole is getting hungrier

The first issue to address is whether this was a singular event or whether it indicates a dramatic change in Sgr A* over the long term. “The big question is whether the black hole is entering a new phase — for example if the spigot has been turned up and the rate of gas falling down the black hole ‘drain’ has increased for an extended period — or whether we have just seen the fireworks from a few unusual blobs of gas falling in,” Mark Morris, another co-author of the paper, explained in the same statement.

Some of these unusual blobs of gas could have come from the star S0-2, which recently passed close to the black hole but did not get sucked in. As the star passed by during summer last year, it could have lost a large portion of gas which took some time to reach Sgr A* before falling in and causing the flares. Alternatively, the black hole could have sucked the outer layer off another object, called G2, which passed close by in 2014. Yet another theory is that large asteroids were drawn into the black hole and caused the flares.

In any case, the scientists reassured the public that Sgr A* may be hungry, but it is no danger to humanity. It is located 26,000 light-years away and would have to be 10 billion times brighter than the highest detected levels to affect us here on Earth.

The findings are published in Astrophysical Journal Letters.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
See the terrifying scale of a supermassive black hole in NASA visualization
Illustration of the black hole Sagittarius A* at the center of the Milky Way.

This week is black hole week, and NASA is celebrating by sharing some stunning visualizations of black holes, including a frankly disturbing visualization to help you picture just how large a supermassive black hole is. Supermassive black holes are found at the center of galaxies (including our own) and generally speaking, the bigger the galaxy, the bigger the black hole.

Illustration of the black hole Sagittarius A* at the center of the Milky Way. International Gemini Observatory/NOIRLab/NSF/AURA/J. da Silva/(Spaceengine) Acknowledgement: M. Zamani (NSF's NOIRLab)

Read more
Supermassive black hole spews out jet of matter in first-of-its-kind image
Scientists observing the compact radio core of M87 have discovered new details about the galaxy’s supermassive black hole. In this artist’s conception, the black hole’s massive jet is seen rising up from the centre of the black hole. The observations on which this illustration is based represent the first time that the jet and the black hole shadow have been imaged together, giving scientists new insights into how black holes can launch these powerful jets.

As well as pulling in anything which comes to close to them, black holes can occasionally expel matter at very high speeds. When clouds of dust and gas approach the event horizon of a black hole, some of it will fall inward, but some can be redirected outward in highly energetic bursts, resulting in dramatic jets of matter that shoot out at speeds approaching the speed of light. The jets can spread for thousands of light-years, with one jet emerging from each of the black hole's poles in a phenomenon thought to be related to the black hole's spin.

Scientists observing the compact radio core of M87 have discovered new details about the galaxy’s supermassive black hole. In this artist’s conception, the black hole’s massive jet of matter is seen rising up from the center of the black hole. The observations on which this illustration is based represent the first time that the jet and the black hole shadow have been imaged together, giving scientists new insights into how black holes can launch these powerful jets. S. Dagnello (NRAO/AUI/NSF)

Read more
Machine learning used to sharpen the first image of a black hole
A team of researchers, including an astronomer with NSF’s NOIRLab, has developed a new machine-learning technique to enhance the fidelity and sharpness of radio interferometry images. To demonstrate the power of their new approach, which is called PRIMO, the team created a new, high-fidelity version of the iconic Event Horizon Telescope's image of the supermassive black hole at the center of Messier 87, a giant elliptical galaxy located 55 million light-years from Earth. The image of the M87 supermassive black hole originally published by the EHT collaboration in 2019 (left); and a new image generated by the PRIMO algorithm using the same data set (right).

The world watched in delight when scientists revealed the first-ever image of a black hole in 2019, showing the huge black hole at the center of galaxy Messier 87. Now, that image has been refined and sharpened using machine learning techniques. The approach, called PRIMO or principal-component interferometric modeling, was developed by some of the same researchers that worked on the original Event Horizon Telescope project that took the photo of the black hole.

That image combined data from seven radio telescopes around the globe which worked together to form a virtual Earth-sized array. While that approach was amazingly effective at seeing such a distant object located 55 million light-years away, it did mean that there were some gaps in the original data. The new machine learning approach has been used to fill in those gaps, which allows for a more sharp and more precise final image.

Read more