Orbital telescopes detect increased activity from the supermassive black hole at the heart of the Milky Way
Three space-based observatories appear to have picked up an unusual increase in activity from the supermassive black hole located at the center of our galaxy. According to the data, the black hole known as Sagittarius A* (Sgr A*), which has a mass of roughly 4 million times our Sun, is throwing out ten times the usual amount of bright X-ray flares.
The discovery was madeby scientists analyzing data from NASA's WISE telescope and ChandraX-ray Observatory, combined with ESA's XMM-Newton platform. Thetelescopes had previously undertaken a long term observation campaignof the region in an attempt to better understand the monster lurkingat the heart of the Milky Way.
The results of thestudy, which drew on data collected over a 15 year span, showed that,under normal circumstances, Sgr A* would be expected to give off asingle bright X-ray flare around once every 10 days. However, for thepast year the leviathanblack hole has been recorded giving off X-ray flares at ten times the standard rate,with one flare being emitted every day.
We know that the flaresare the result of superheated gas being drawn into a black hole. Thequestion then becomes, what is the source of this extra gas? Ourcurrent understanding of black holes is still relatively rudimentary,leaving scientists unable to pin down exactly what is causing theincrease in activity. The two leading theories on the increasedemissions involve the passing of a body known as G2, and an increase in intensity of the stellar wind from huge stars nearby, forcing larger quantities of material toward the black hole and increasing the monster's feeding rate.
It was initiallyassumed that G2 was simply a mass of dust and gas. However,observations of the body after passing Sgr A* do not exhibit thelevels of distortion that would be expected of such a body passing bya supermassive black hole. It has since been suggested that G2 is infact the extended cocoon of a large star, the gravity of which keptmuch of the surrounding gas and dust from being siphoned off into Sgr A*.
Astronomers had first believed that the close proximity pass of G2 had no effecton the black hole, however further analysis of data from the orbitalassets revealed that it was relatively soon after the passing of G2that the brightness and frequency of the flares increased.
The observations backthe idea that material stripped away from the passing cloud couldtheoretically be responsible for the increase in bright X-rayemissions, though it could still be the result of a cosmiccoincidence.
"It’s too soon tosay for sure, but we will be keeping X-ray eyes on Sgr A* in thecoming months," states co-author of a paper on the research, BarbaraDe Marco of the Max Planck Institute for Extraterrestrial Physics in Germany. "Hopefully, new observations will tell us whether G2 isresponsible for the changed behavior or if the new flaring is justpart of how the black hole behaves."
The preprint of a paperon the findings can be found on the Cornell University page prior toits upcoming publication in the Monthly Notices of the Royal AstronomicalSociety.