It seems that our current global pandemic is even starting to affect science writers. The Massachusetts Institute of Technology (MIT) press release on our first story starts: It seems the universe has an odd sense of humor. While a crown-encrusted virus has run roughshod over the world, another entirely different corona about 100 million light-years from Earth has mysteriously disappeared.

In space-related sciences, a corona is the region of superheated gas surrounding an object like our Sun or a black hole. Objects that have the same spiky, surrounding structure, like corona-viruses, get their names from the much bigger and meaner celestial originals. 

In this case, the corona in question is the biggest and meanest of all: it is the corona around a galaxy’s supermassive black hole. 

In a new paper published in the Astrophysical Journal Letters with lead author Claudio Ricci, astronomers document the fade away of the X-ray corona of galaxy 1ES 1927+654. Using the Neutron Star Interior Composition Explorer (NICER) X-ray observatory on the International Space Station, they say this system faded by a factor of 10,000 over just forty days, and then, after one hundred days of quiet, it rose back up in brightness to be twenty times brighter than before.

The corona around supermassive black holes in galaxies is created by material getting superheated as it falls into the black hole via an accretion disc, and the best way to explain this kind of a temporary fading is through a disruption in that accretion disc. They theorize that a runaway star may have wandered too close to the center of this galaxy and been disrupted by the supermassive black hole, and its debris may have, in turn, disrupted the accretion disk. According to Ricci: We just don’t normally see variations like this in accreting black holes. It was so strange that at first, we thought maybe there was something wrong with the data. When we saw it was real, it was very exciting. But we also had no idea what we were dealing with; no one we talked to had seen anything like this.

Erin Kara, a co-author of this study, goes on to explain: This dataset has a lot of puzzles in it. But that’s exciting because it means we’re learning something new about the universe. We think the star hypothesis is a good one, but I also think we’re going to be analyzing this event for a long time.

Astronomy can be super frustrating. We can’t run experiments or recreate galaxy-spanning events in our labs. When we see weird and rare events, it is thanks to the luck of looking in the right place at the right time, and the one data set we collect may be the only one we collect. While the idea of an infalling star is a solid one that fits the data, we may never know if this is what actually happened. All we know for sure is that a supermassive black hole’s corona 300 million light-years away faded for forty days and came back brighter than ever before. 

More Information

MIT press release 

NASA Jet Propulsion Laboratory press release 

“The Destruction and Recreation of the X-Ray Corona in a Changing-look Active Galactic Nucleus,” C. Ricci et al., 2020 July 16, Astrophysical Journal Letters (Preprint on arxiv.org)