Astronomer Joins in Study of Two Million Light Year Extragalactic Afterburner
MELBOURNE, FLA.—Blasting over two million light years from the center of a distant galaxy is a supersonic jet of material that looks strikingly similar to the afterburner exhaust of a fighter jet, except in this case the jet engine is a supermassive black hole and the jet material is moving at nearly the speed of light.
Eric Perlman, Florida Institute of Technology professor of physics and space science, contributed to research published this month in the Astrophysical Journal Letters. The study shows the galaxy-scale jet to have similar bright and dark regions as the phenomenon in an afterburner exhaust called “shock diamonds.”
A new image of the previously studied jet taken with the Australia Telescope Compact Array, reveals regularly spaced areas that are brighter than the rest of the jet in a pattern that echoes the way the afterburner from a jet engine has brighter diamond-shaped areas in its general glow.
“One intriguing possibility is that the pattern we see in this cosmic jet is produced in the same way as the pattern in the exhaust from fighter jet engines,” said lead-author Leith Godfrey, from the Curtin University node of The International Centre for Radio Astronomy Research.
The jets are produced when material falls onto a supermassive black hole at the center of a galaxy about 13 billion light years away, but many details beyond that remain unknown. “Massive jets like this one have been studied for decades, since the beginning of radio astronomy, but we still don’t understand exactly how they are produced or what they’re made of,” said Godfrey.
“If the brighter patches are caused by re-confinement shocks as they are in earthly jet engines, then the distance between them tells us that the black hole ‘engine’ produces more power in one second than the sun does in 80,000 years.”
“This new image of the jet shows detail we’ve never seen before and the pattern we revealed provides a clue to how jets like this one work,” said Jim Lovell, a co-author from the University of Tasmania.
“This particular jet emits a lot of X-rays, which is hard to explain with our current models. Our new find is a step forward in understanding how these giant objects emit so much X-ray radiation, and indirectly, will help us understand how the jet came to be.”
Equally mysterious to astronomers, the pattern persists for nearly a million light years, despite the fact that the jet has in the process propagated through the entire host galaxy, as well as the surrounding cluster. Understanding how this occurs may give us clues to the makeup of the jets.
“One might expect that as it passes through the galaxy, the jet would lose energy and begin to dissipate. But this jet and others like it appear to propagate almost undisturbed, and can even become re-energized well after they leave the galaxy,” said co-author Perlman.
“The new image bolsters the case that the jet plasma is moving at only one percent less than the speed of light, as we inferred from the first image taken with the Chandra X-ray Observatory,” said Herman L. Marshall of Massachusetts Institute of Technology, a co-author. It looks like rocket engine exhaust, as in this YouTube video:
Leith Godfrey et al. “Periodic Structure in the megaparsec-scale jet of PKS 0637-752” Published in The Astrophysical Journal Letters, Vol 758 Number 2.