NASA noticed that the normally calm region near the black hole at the very center of our galaxy flared up at least twice over the past century.
The researchers looked at " rapid variations in the X-ray emission from gas clouds surrounding the supermassive black hole," nicknamed Sgr A*, a NASA news release reported. The team believes "light echoes" are responsible for these variations.
The echoes could have been spawned when material, possibly from a planet or star, fell into the black hole. This would have cause X-rays that bounced off gas cloud up to a hundred light-years away.
The phenomenon can be compared to a human's voice "echoing" off a canyon wall.
These echoes have been spotted before, but this is the first time both instances are represented within a single body of data.
The visible light allows astronomers to observe what the massive black hole was doing long before humans even knew it existed.
"The X-ray echoes suggest that the area very close to Sgr A* was at least a million times brighter within the past few hundred years. X-rays from the outbursts (as viewed in Earth's time frame) that followed a straight path would have arrived at Earth at that time. However, the reflected X-rays in the light echoes took a longer path as they bounced off the gas clouds and only reached Chandra (the telescope) in the last few years," the news release reported.
The X-ray emissions shown in the video below are created from a process called fluorescence.
This takes place when "iron atoms in these clouds have been bombarded by X-rays, knocking out electrons close to the nucleus and causing electrons further out to fill the hole, emitting X-rays in the process. Other types of X-ray emission exist in this region but are not shown here, explaining the dark areas," the news release reported.
There are several possible explanations for the outbursts: a jet produced by the disruption of a nearby star, Sgr A* collecting debris from "close encounters" between two stars, an increase in Sgr A*'s material consumption due to clumps of gas let off by massive nearby stars, or possibly even a magnetar, which is a neutron star with an extremely strong magnetic field.
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