NEWS | March 10, 2020

NRL Scientist Discovers Monstrous Black Hole Explosion

By Cassandra Eichner, U.S. Naval Research Laboratory Corporate

WASHINGTON — U.S. Naval Research Laboratory researchers led a team that discovered the most energetic outburst from a supermassive black hole.

The scientists played a key role in discovering evidence for the most powerful black hole outburst in the universe that occurred about 400 light years away in the Ophiuchus galaxy cluster. The findings were published February 2020 in The Astrophysical Journal.

NRL Radio Astronomer Simona Giacintucci discovered the outburst using her expertise in special imaging tools to see images of low frequency radio waves. The discovery combined and analyzed data and imagery from NASA’s Chandra X-ray space observatory and XMM-Newton X-ray telescopes floating in space, Murchison Widefield Array (MWA) low frequency radio telescope in Australia, and Giant Metrewave Radio Telescope (GMRT) in India.

Chasing Dinosaurs

Innate curiosity drove Giacintucci’s discovery. She became intrigued after reading a paper published in 2016 by Chandra expert Norbert Werner and his collaborators. Werner observed the Ophiuchus galaxy cluster with the Chandra satellite and noticed a very sharp feature that looked like a curved edge in the x-ray image of the cluster. They thought it could be the edge of a giant cavity, but could not see the whole cavity because the field of view from the telescope was too small.

“They calculated how big and how energetic the black hole outburst should have been to produce such a large cavity,” Giacintucci said. “They thought it was too high – so, they thought the edge was related to another process and not an outburst.”

Giacintucci decided to investigate. Her work observing galaxy clusters led her to examine available radio data over the past several years.

“When I looked at the low-frequency images of Ophiuchus I saw this big radio structure,” Giacintucci said. “This radio emission perfectly fills the X-ray cavity like a hand in glove, so they both have to be the result of a huge black hole outburst and not something else.”

“When Norbert Werner and collaborators published the X-ray data, they didn’t have these new sensitive radio images,” she said. “So, they dismissed the possibility that this was a black-hole-driven cavity. When we found the radio emission, then one plus one became two. It all added up. This is how we ended up discovering this dinosaur.”

The research team refers to their findings as fossils or dinosaurs because the cosmic events occurred in the past, and researchers are able to see their fading, but inactive remains in the form of electromagnetic emissions across the electromagnetic spectrum.

The Center of Ophiuchus

At the center of Ophiuchus exists a super massive black hole. It pulls in the surrounding gas and releases energy in the form of radio jets — a source of radio wave emission. Researchers believe these jets heat up and push away the accreting gas, regulating the black hole’s food supply. This theory still puzzles scientists.

The black hole’s outburst was hot and huge. In theory, such an event would heat up and shred all the areas surrounding it to pieces. But when researchers looked at the x-ray images, they saw an area with cool air near the center of the cluster.

“There are questions about how such a powerful black hole outburst could have not completely destroyed the center of the cluster which researchers still see there,” she said. “It is interesting we see cool gas in the center despite this powerful and energetic explosion.”

The finding challenged current theories on how gas around a black hole remains stable. As technology and telescopes advance, Giacintucci believes more of these mysteries will be uncovered.

“We believe the more we observe the more we can find dinosaurs and we have just unveiled the first example,” Giacintucci said.

About the U.S. Naval Research Laboratory Remote Sensing Division

The Remote Sensing Division conducts a program of basic research, science, and applications aimed at the development of new concepts for sensors and imaging systems for objects and targets on the Earth, in the near-Earth environment, and in deep space.

Astrophysicists in the remote sensing division perform extensive research in the ionosphere, often using low-frequency radio interferometers. Events in the ionosphere significantly impact a variety of communications and navigation equipment used by military operators. Their research and expertise using interferometers and the data they provide offers a unique opportunity to perform research into galaxies far beyond the Milky Way.

About the U.S. Naval Research Laboratory

NRL is a scientific and engineering command dedicated to research that drives innovative advances for the Navy and Marine Corps from the seafloor to space and in the information domain. NRL headquarters is located in Washington, D.C., with major field sites in Stennis Space Center, Mississippi; Key West, Florida; and Monterey, California, and employs approximately 2,500 civilian scientists, engineers and support personnel.