NASA’s Hubble Space Telescope has captured dramatic images of a set of wispy, green objects near dead quasars, which once flickered into life and then faded.
According to NASA, the images that were taken by Hubble show that the glowing structures have looping, helical, and braided shapes. Astronomers believe that the discovery will shed more light on the baffling behavior of galaxies with energetic cores.
Astronomers believe that these phantom wispy structures outside the host galaxy could have been illuminated by powerful ultraviolet radiation from a supermassive black hole at the center of the host galaxy. The most active of these galaxy cores are called quasars, which shine material heated to a point that sends a bright beam into deep space.
Bill Keel, researcher from the University of Alabama, and lead author of the study, said, “However, 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. 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.”
According to the astronomers, the quasars may be in fact co-orbiting black holes, which could change the quasar’s brightness as they circle each other, acting something like a cosmic dimmer switch. They also believe that a process known as photoionization is causing the once-invisible filaments in deep space to glow green. In the process oxygen atoms in the filaments absorb energy from the quasar and slowly re-emit it as light for many thousands of years. Other elements present in the filaments include hydrogen, helium, nitrogen, sulfur and neon.
The astronomers added that the green filaments are long tails of gas disintegrated under gravitational forces when two galaxies merged, and are tens of thousands of years old. They are slowly orbiting their host galaxy, long after the merger was completed.
“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. Potentially, you can say we’re seeing it 1.5 billion years after a smaller gas-rich galaxy fell into a bigger galaxy,” added Keel.