Scientists believe there is a supermassive black hole at the center of the Milky Way galaxy named Sagittarius A*. This black hole is 26,000 light-years from the Earth and approximately 4 million times the mass of the Sun.
While Sgr A* has always been thought of as a quiet, relatively modest black hole, new observations show a recent burst of unprecedented activity suggesting it is on a sudden feeding frenzy.
The observations comes from a research team at the UCLA Galactic Center Group, which published their work in Astrophysical Journal Letters. Using the W.M. Keck Observatory in Hawaii and the European Southern Observatory’s Very Large Telescope in Chile, the team gathered 13,000 images of the accretion disk area of the black hole.
The accretion disk is where enormous amounts of gas, dust, and radiation accumulate and orbit outside the “point of no return”—or the event horizon. According to their observations, there has been a sudden and “unprecedented” increase in brightness from the Sgr A* accretion disk.
The paper’s co-author, Andrea Ghez, UCLA professor of physics and astronomy, stated:
“We have never seen anything like this in the 24 years we have studied the supermassive black hole. It’s usually a pretty quiet, wimpy black hole on a diet. We don’t know what is driving this big feast.”
Scientists say the increase in brightness means the black hole is consuming more interstellar material, including stars, planets, dust, gas, and asteroids. One of the research team’s lead authors originally believed the glow was a star because Sagittarius A* had never been observed at that level of brightness.
The advanced techniques used to gather this information is perhaps one of the most noteworthy aspects of this story. The researchers employed speckle holography to extract and analyze distant information from Sgr A* during the last 24 years. Another technique, called adaptive optics, eliminates distortion from Earth’s atmosphere. Combined, researchers were able to conclude that this is the largest amount of radiation detected from our galaxy’s black hole in nearly a quarter of a century.
Mark Morris, another co-author and UCLA professor of physics and astronomy, speculated on the cause of the increase:
“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.”
Scientists believe that by recording and analyzing such increases in black hole activity, they can get a better understanding of how black holes evolve and impact the development of galaxies.