In images from the decommissioned Spitzer Space Telescope, streams of dust thousands of light-years long flow toward the supermassive black hole at the center of the Andromeda Galaxy. It turns out that these currents can explain how black holes that are only billions of times the mass of our Sun satisfy their great hunger but remain "quiet" eaters
In images from the decommissioned Spitzer Space Telescope, streams of dust thousands of light-years long flow toward the supermassive black hole at the center of the Andromeda Galaxy. It turns out that these currents can explain how black holes with billions of times the mass of our Sun satisfy their great hunger but remain "silent" eaters.
When supermassive blacks gobble up gas and dust, the matter heats up a bit before falling in, creating amazing light displays – sometimes brighter than an entire galaxy full of stars. As the matter decays into clumps of different sizes, there are fluctuations in the brightness of the black hole.
But the black holes at the center of the Milky Way (Earth's home galaxy) and at the center of Andromeda (one of our closest neighboring galaxies) are among the quietest eaters in the universe. The brightness of the little light they emit doesn't change much, and is made better by the fact that they eat a small but steady stream of food, rather than large chunks. The currents approach the black hole in small portions, and in a spiral, similar to the eddies that water creates when it drains from a sink.
A study published earlier this year took the assumption that a quiescent supermassive black hole is fed by a steady stream of gas and applied it to the Andromeda galaxy. Using computer models, the authors simulated how gas and dust near 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 continuously feed it. Many streams of gas and dust can refill and sustain the disk.
But the researchers also found that these streams must stay at a certain size and flow rate because otherwise the material would fall into the black hole in regular clumps, causing more fluctuations in the light.
When the researchers compared their findings with data from the Spitzer and Hubble space telescopes, they found spirals of dust that Spitzer had previously identified that fit these constraints. The researchers deduced from this that the spirals feed Andromeda's supermassive black hole.
Spitzer, launched in 2003, studied the universe with AI light, which is invisible to the human eye. Different wavelengths reveal different things in Andromeda, including hotter light sources like stars, and colder ones like dust.
Separating these wavelengths and looking at the dust alone allows scientists to see the "skeleton" of the galaxy - places where gas condensed and cooled, sometimes creating dust that creates conditions for star formation. This look at Andromeda reveals a few surprises. For example, although it is a spiral galaxy like the Milky Way, Andromeda is dominated by a large ring of dust rather than the obvious arms surrounding its center. The images also revealed a secondary hole in one part of the ring that a dwarf galaxy had passed through.
For the article on the Spitzer Space Telescope website
More of the topic in Hayadan:
