Ghosts of Quasars Past—Hubble Telescope Reveals Phantom of Eight Galaxies

In a new series of images captured by NASA's Hubble Space Telescope, researchers with the US space agency discovered an eery green hue spiraling and braiding shapes around eight active galaxies. And while the wisps of glowing structures "don't fit a single pattern", lead researcher of the study, Bill Keel believes that the bright green lights may reveal the high energy at the core of these eight galaxies.

Believed to be illuminated by powerful UV radiation from a supermassive black hole at the core of the host galaxy, the green light is thought to have been emitted by quasars which superheat gas as it spins around the black hole. But even though quasars are not too unique in terms of cosmic phenomena, these eery green lights appear to be something unlike anything researchers have seen before.

"The quasars are not bright enough now to account for what we're seeing; this is a record of something that happened in the past," Keel says. "The glowing filaments are telling us that the quasars were once emitting more energy, or they are changing very rapidly, which they were not supposed to do."

Instead of a single black hole, Keel posits that perhaps a pair of co-orbiting black holes could be to blame for the unique circumstances they're finding in these eight active galaxies.

But it's not a new phenomenon that we're seeing on film. In fact, Keel says that the green wisps could be indicative of a galactic merger that happened millions of years ago. When the gases were ionized in the process of the merger, a bright searchlight was sent deep out into space, and now we're seeing the aftermath as it occurred millennia ago.

"We see these twisting dust lanes connecting to the gas, and there's a mathematical model for how that material wraps around in the galaxy," Keel says. "Potentially, you can say we're seeing it 1.5 billion years after a smaller gas-rich galaxy fell into a bigger galaxy."

So, why are all eight of the goblin green shapes unique?

The green filaments are believed to be long gaseous tails of the quasar which are spun into unique shapes by the gravitational pull of each galaxy they are hosted in. And further research conducted by the Kitt Peak National Observatory reveals that these gas clouds can extend for more than 30,000 light-years outside of the host galaxy. Talk about a big cloud!