Eating too fast is not good for you, whether you’re a person or a supermassive black hole. Astronomers have now caught a black hole at the center of NGC 5195 with a case of galactic indigestion, which has consequences for the entire galaxy.
NGC 5159 is the elliptical companion to the Whirlpool Galaxy. The two objects are performing a cosmic ballet, whereby NGC 5159 crosses the larger galaxy's disk every few hundred million years. At every passage, the galaxies exchange gas and the voracious supermassive black hole, which weighs around 19 million Suns, tries to gobble up as much as possible.
But when it’s full, all that material gets blasted back out. Researchers from the Jodrell Bank Centre for Astrophysics have worked out how the portentous eruption of materials happens and how they move across the dwarf galaxy. The study was presented at the National Astronomy Meeting this week.
Electrons from the material accelerate near the black hole to near the speed of light. The particles begin to emit a lot of radiation, which slams on the gas in the interstellar medium. The heated gas expands quickly, creating shockwaves. The shocked gas gets even hotter, reaching millions of degrees and forming a clearly detectable arc. In cosmic terms, this happened very recently.
“The age of the arcs in NGC 5195 is 1-2 million years," project leader Dr Hayden Rampadarath said in a statement. "To put that into context, the first traces of matter were being forced out of the black hole in this system at about the time that our ancestors were learning to make fire. That we are able to observe this event now through such a range of astronomical facilities is quite remarkable."
The research was possible thanks to high-resolution radio images taken by the e-MERLIN array, which Jodrell Bank is part of. The team combined these observations with multiple views of the system taken with different instruments, like the Very Large Array (VLA), NASA’s X-ray Observatory Chandra, as well as the Hubble Space Telescope.
“Comparing the VLA images at radio wavelengths to Chandra’s X-ray observations and the hydrogen-emission detected by Hubble, shows that features are not only connected, but that the radio outflows are in fact the progenitors of the structures seen by Chandra and Hubble," said Rampadarath. "This is an event of galactic proportions that we can see right across the electromagnetic spectrum.”
The Whirlpool Galaxy is an example of a minor merger, where a larger galaxy slowly cannibalized a smaller galaxy. The system is relatively close to us, just 23 million light-years away.
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