Scientists have discovered an ancient ‘fossil’ within a distant galaxy. Researchers believe this structure was formed following an eruption from its central black hole millions of years ago.
NASA announced on January 11 that a team of researchers has discovered another clue to galactic evolution in the NGC 4945 galaxy, located 13 million light-years away. NGC 4945 is known as an active starburst galaxy, forming stars much faster than our galaxy, and has an actively feeding black hole at its center surrounded by a cloud of dust called a torus.
Scientists using data from NASA’s Chandra X-ray Observatory and European Space Agency’s satellite XMM-Newton (X-ray Multi-Mirror Mission) discovered an “iron K-alpha line,” a phenomenon that occurs when X-rays from a black hole’s accretion disk interact with cold gas. Although this phenomenon often occurs in active galaxies, scientists initially believed it occurred much closer to the black hole.
“Chandra has mapped iron K-alpha in other galaxies. In this one, it helped us study individual bright X-ray sources in the cloud to help us rule out other potential origins besides the black hole,” said Jenna Cann, a co-author of the study, according to NASA. “But NGC 4945’s line extends so far from its center that we needed XMM-Newton’s wide field of view to see all of it.”
XMM-Newton mapped the extent of the iron line 32,000 light years along the galaxy’s plane and 16,000 light years above, much larger than those previously recorded. Scientists believe the line originates from a particle jet emitted by the central black hole five million years ago.
These researchers hope to use this data to inform deeper studies on the galaxy and how the central black hole is changing it.
“There are a number of lines of evidence that indicate black holes play important roles in some galaxies in determining their star formation histories and their destinies,” said Edmund Hodges-Kluck, co-author of the study, according to NASA. “We study a lot of galaxies, like NGC 4945, because while the physics is pretty much the same from black hole to black hole, the impact they have on their galaxies varies widely. XMM-Newton helped us discover a galactic fossil we didn’t know to look for – but it’s likely just the first of many.”
Researchers have long been studying supermassive black holes, theorizing they play a role in galaxy formation. Scientists revealed a much sharper image of the supermassive black hole at the heart of the Messier 87 galaxy 55 million light-years from Earth last year, as previously reported by The Dallas Express.
