14 DAY TRIAL // The majority of galaxies have a black hole at their core and our Milky Way is no exception. This black hole that resides at the center of our home galaxy goes by the name Sagittarius A* and is estimated to hold the mass equivalent of around 4 million Suns.
With the help of telescopes, astronomers have been studying its behavior for years now. They say that, like all other black holes, it spends its days devouring its surroundings and producing X-ray flares.
Interestingly, data delivered by NASA's Chandra X-ray Observatory, ESA's XMM-Newton and the Swift satellite shows that, as of recently, Sagittarius A* has grown restless.
In a study in the journal Monthly Notices of the Royal Astronomical Society, astronomers explain that, usually, our galaxy's central black hole would spew out bright X-ray flares at a rate of just one every 10 days or so. Over the past year, however, Sagittarius A* has become hyperactive.
“Three orbiting X-ray space telescopes have detected an increased rate of X-ray flares from the usually quiet giant black hole at the center of our Milky Way galaxy after new long-term monitoring,” researchers say.
Apparently, Sagittarius A* is now coughing out X-ray flares at a rate of one every day. This is a 10-fold increase when compared to its normal routine that was documented by scientists over the past 15 years.
A possible explanation
It was back in 2002 that astronomers spotted a mysterious object circling Sagittarius A*. Then, last year, this mysterious object, dubbed G2, came as close as 30 billion kilometers (about 18.6 billion miles) of the black hole.
As it turns out, it was soon after this visit that Sagittarius A* grew restless and began producing X-ray flares more often than it usually did. Hence, it could be that the black hole's abnormal behavior is the result of its close encounter with G2.
When G2 was first documented, scientists thought it to be merely a mammoth cloud of gas and dust. Now, they are more inclined to think that it is actually a proper star shrouded in a cocoon of gas and dust.
Since bright X-rays flares are the result of hot material flowing toward Sagittarius A*, it could be that the black hole's recent behavior was triggered by matter being stripped away from G2 and sent in its direction, scientists suspect.
“The fact that Sgr A* became more active not long after G2 passed by suggests that the matter coming off of G2 might have caused an increase in the black hole’s feeding rate,” says researcher Mark Morris.
Then again, it could also be that black holes simply have a habit of going through such hyperactive phases and that Sagittarius A*'s behavior in recent months has nothing to do with having been visited by G2, whatever this object might be.
“Hopefully, new observations will tell us whether G2 is responsible for the changed behavior or if the new flaring is just part of how the black hole behaves,” explains astronomer Barbaro de Marco.
