The monster black holes the centres of galaxies are typically surrounded by searing clouds of hot gas. As this material funnels toward the black hole, it can create cosmic auras around the darkest place in the galaxy.
Strangely, the black hole at the centre of the Milky Way galaxy isn’t nearly as bright as it should be. Figuring out the mystery of why this black hole is so dim, relatively speaking, will help clarify the connection between the light that we see and what falls in.
There are a number of ways that black holes can appear to glow. When gas from nearby stars falls toward the black hole, the gas spirals like water going down a drain. As it does so, it rubs together and gets hot. The gas that is hot pulls its own atoms apart, creating a sea of ions and electrons.
These churning charged particles generate turbulent magnetic fields, which funnel the gas into two jets pointing in opposite directions. If one of these jets happens to be angled so that it’s pointing toward Earth, we see a brilliantly bright black hole. But sometimes we don’t have to be located directly in the path of the fire hose. Those jets can also stream out and slam into nearby clouds of gas or even a neighbouring galaxy. The collision generates a distinct glow.
– Neha
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