A suspected supernova is actually something much rarer

In a case of comic book misidentity, an international team of astronomers has revealed that what they once thought to be a supernova is actually a periodic flaring of a galaxy where a supermassive black hole gives off bursts of energy every 114 days as it tears pieces from an orbit. star.

Six years after its initial discovery – reported in The Astronomer’s Telegram by Thomas Holoien of Carnegie – researchers, led by Anna Payne of the University of Hawaii at Mānoa, can now say that the phenomenon they observed, called ASASSN- 14kb, is a periodic phenomenon. recurrent eruption from the center of a galaxy more than 570 million light years away in the southern constellation of Pictor.

Their findings – based on 20 cases of regular seizures – will be published in the Astrophysics Journal and presented by Payne at the annual meeting of the American Astronomical Society.

Active galaxies, such as the host of ASASSN-14kb, have unusually bright and variable centers. These objects produce much more energy than the combined contribution of all their stars. Astrophysicists believe this is due to gravitational and frictional forces heating a swirling disc of gas and dust that collects around the central supermassive black hole. The black hole slowly consumes the material, creating random low-level changes in the light emitted by the disk.

This is the first unambiguous example of such clockwork behavior of an active galaxy. Periodically recurring eruptions, such as those of ASASSN-14kb, could be evidence of elusive observational cosmic phenomena that were previously predicted by theorists.

“Knowing the timing of this extragalactic Old Faithful allows us to coordinate it and study it in more detail,” Payne said.

ASASSN-14ko was first detected by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global network of 20 robotic telescopes headquartered at Ohio State University (OSU) in Columbus. When Payne examined all of the ASAS-SN data on the phenomenon, she noticed a series of 17 evenly spaced flares.

Based on this finding, astronomers predicted the galaxy would experience another explosion on May 17 last year and coordinated ground and space facilities to make observations. Since then, they have successfully predicted and observed flares on September 7 and December 26.

“ASAS-SN is designed to probe the physics of our universe by looking for transient and variable events.” Said Holoien. “It’s exciting that the light object we originally thought was a violent supernova explosion – which would be interesting in itself, but more common – turned out to be a much sought-after cosmic event.

So, what causes repeated breakouts? The team considered several possible explanations, but believe the most likely is what’s called a partial tidal disturbance event.

Tidal disturbance events, or TDEs, occur when a star gets too close to a supermassive black hole, tearing it to shreds. Some of its material is thrown into space and the rest falls back onto the black hole, forming a hot, shiny disk of gas when consumed.

In this case, instead of a star being obliterated by interaction with the black hole, it would be slowly stripped during each orbit. Eruptions occur when the lost matter – equal to three times the mass of Jupiter on each pass – falls towards the black hole.

Astronomers don’t know how long rockets will persist. The star cannot lose mass forever, and while scientists can estimate how much mass it loses in each orbit, they don’t know how much it originally had.

“We plan to continue to predict and observe these bursts or for as long as possible,” said second author Benjamin Shappee, also of UH Mānoa (and a former Carnegie student). “This rare find could reveal new details about the physics of black holes.”