Why monster black holes satiate their big appetites but remain quiet eaters?

Using archival data from NASA's retired Spitzer Space Telescope, scientists have gained new insights into why some supermassive black holes are less luminous yet more consistent in their brightness than others.

Images acquired by NASA's retired Spitzer Space Telescope show streams of dust thousands of light-years long flowing toward the supermassive black hole at the heart of our neighbouring Andromeda galaxy. Scientists believe these streams can help explain how these colossal bodies satiate their big appetites but remain quiet eaters.

Supermassive black holes are known for their ability to consume vast amounts of gas and dust, which heats up dramatically just before falling in. Typically, this process results in variable brightness, as the material is consumed in uneven clumps. However, the study suggests that both the black holes in the center of the Milky Way and Andromeda maintain a quiet demeanor. The light they emit does not vary significantly in brightness, suggesting they are consuming a small but steady flow of food, rather than large clumps.

The research team utilized computer models to simulate the behavior of gas and dust near Andromeda's supermassive black hole over time. Their models indicated the formation of a small disk of hot gas close to the black hole, which could continuously supply it with the necessary material to maintain its luminosity without significant fluctuations.

The researchers also found that those streams must stay within a particular size and flow rate, otherwise the matter would fall into the black hole in irregular clumps, causing more light fluctuation.

The researchers compared their recent findings to the data collected by Spitzer and NASA's Hubble Space Telescope. They found spirals of dust that had previously been identified by Spitzer and fit within their study's constraints. Based on this comparison, the authors concluded that these spirals are feeding Andromeda's supermassive black hole.

How does a black hole eat?The Andromeda Galaxy, our cosmic neighbor, is fed by rivers of galactic dust that flow into the supermassive black hole at its center.This tasty treat dropped just in time for #BlackHoleWeek. https://t.co/aGsgAIrPJY pic.twitter.com/ZBX92UbnJC

— NASA JPL (@NASAJPL) May 9, 2024