These images of the Andromeda Galaxy use data from NASA’s retired Spitzer Space Telescope. The top image shows multiple wavelengths, revealing stars, dust, and regions of star formation. The bottom image shows only dust, making it easier to see the underlying structure of the galaxy. Credit: NASA/JPL-Caltech
NASAThe images from the Spitzer Space Telescope show dust streams feeding the supermassive black hole in Andromeda, showing how these black holes can feed continuously without significant light fluctuations. Recent studies using computer models and archival data support this finding.
In images from NASA’s retired Spitzer Space Telescope, dust streams thousands of light-years long are flowing toward the supermassive black hole at the heart of the Andromeda galaxy. It turns out that these currents may help explain how black holes, billions of times the mass of our sun, satisfy their great hunger but remain ‘silent’ eaters.
As supermassive black holes swallow gas and dust, the material heats up just before it falls in, creating incredible light shows – sometimes brighter than an entire galaxy full of stars. When the material is consumed in clumps of different sizes, the black hole’s brightness fluctuates.
But the black holes at the center of the Milky Way (Earth’s home galaxy) and Andromeda (one of our closest galactic neighbors) are among the quietest eaters in the universe. The little light they emit does not vary significantly in brightness, indicating that they consume a small but steady stream of food, rather than large clumps. The streams approach the black hole little by little and in a spiral, similar to the way water swirls down a drain.
Hunting for Andromeda’s food source
A study published earlier this year took the hypothesis that a silent supermassive black hole feeds on a steady stream of gas and applied it to the Andromeda Galaxy. Using computer models, the authors simulated how gas and dust in the vicinity of Andromeda’s supermassive black hole might behave over time. The simulation showed that a small disk of hot gas could form close to the supermassive black hole and feed it continuously. The disk could be replenished and maintained by countless streams of gas and dust.
But the researchers also discovered that those flows must remain within a certain size and flow rate; otherwise, the matter would fall into the black hole in irregular clumps, causing more light fluctuations.
This close-up of the center of the Andromeda Galaxy, taken by NASA’s retired Spitzer Space Telescope, features dashed blue lines to mark the path of two dust streams flowing toward the supermassive black hole at the galaxy’s center (indicated by a purple color). point). Credit: NASA/JPL-Caltech
When the authors compared their findings to data from Spitzer and NASA’s Hubble Space Telescope, they found dust spirals previously identified by Spitzer that fit these constraints. From this, the authors concluded that the spirals feed Andromeda’s supermassive black hole.
“This is a great example of scientists re-examining archival data to reveal more about galaxy dynamics by comparing it with the latest computer simulations,” said Almudena Prieto, an astrophysicist at the Canary Islands Institute of Astrophysics and the University Observatory Munich. co-author of the study published this year. “We have 20 years of data that tells us things we didn’t recognize when we first collected them.”
A deeper look at Andromeda
Launched in 2003 and operated by NASA’s Jet Propulsion Laboratory (JPL), Spitzer studied the universe in infrared light, which is invisible to the human eye. Different wavelengths reveal different features of Andromeda, including hotter light sources, such as stars, and cooler sources, such as dust.
By separating these wavelengths and looking just at the dust, astronomers can see the “skeleton” of the Milky Way: places where gas has coalesced and cooled, sometimes creating dust, creating the conditions for stars to form. This look at Andromeda revealed a few surprises. For example, although it is a spiral galaxy like the Milky WayAndromeda is dominated by a large dust ring rather than individual arms circling its center. The images also revealed a secondary hole in part of the ring through which a dwarf galaxy passed.
Andromeda’s proximity to the Milky Way means it appears larger than other galaxies from Earth: seen with the naked eye, Andromeda would be about six times as wide as the moon (about 3 degrees). Even with a field of view wider than Hubble’s, Spitzer had to take 11,000 snapshots to create this comprehensive view of Andromeda.
More about the mission
JPL managed the Spitzer Space Telescope mission for NASA’s Science Mission Directorate in Washington until the mission was axed in January 2020. Science operations were conducted at the Spitzer Science Center at Caltech. Spacecraft operations were based at Lockheed Martin Space in Littleton, Colorado. Data are archived in the Infrared Science Archive, managed by IPAC at Caltech. Caltech manages JPL for NASA.