New observations could allow researchers to better-understand the black hole in the center of our galaxy.
Over the past seven years NASA's Swift spacecraft a treasure-trove of images that show X-ray flares around the Milky Way's black hole Sagittarius A* (Sgr A*), a NASA news release reported.
The giant black hole sits 26,000 light-years away in the center of our galaxy. It has a mass of four million times that of the sun but does not appear as bright as researchers would expect.
"Given its size, this supermassive black hole is about a billion times fainter than it could be," Nathalie Degenaar, principal investigator on the Swift galactic center campaign and an astronomer at the University of Michigan in Ann Arbor, said in the news release. "Though it's sedate now, it was quite active in the past and still regularly produces brief X-ray flares today."
Researchers hoped to learn more about the mysterious black hole, so they programmed the Swift spacecraft to take a 17-minute-long snapshot of the Milky Way's center every few days.
The team is excited for the craft to observe an upcoming close-call between a cold gas cloud called G2 that is about three times the mass of Earth and Sgr A* .
The gas cloud is already being affected by Sgr A*'s intense gravitational pull, and researchers believe when it gets close enough it will heat up and produce X-rays.
"Astronomers around the world are eagerly awaiting the first sign that this interaction has begun," Jamie Kennea, a team member at Pennsylvania State University, said. "With the invaluable help of Swift, our monitoring program may well provide that indicator."
If some of the gas cloud actually reaches Sgr A* the black hole will most likely show an increase in activity.
In April the team thought the interactions had started after they detected a burst of X-ray light and increase in activity in the Sgr A* region; they were excited to discover the event was actually caused by a completely separate entity than G2. The researchers found the activity was caused by a "rare subclass of neutron star."
A neutron star is "the crushed core of a star destroyed by a supernova explosion, packing the equivalent mass of a half-million Earths into a sphere no wider than Washington," the news release reported. Only 26 of this particular type of star, called magnetars, have been spotted in the past.
The team hopes the interaction between neutron star f SGR J1745-29 and Sgr A* will allow them to test Einstein's theory of relativity. They would do this by detecting "subtle changes" in the neutron star's regular X-ray and radio pulse timing due to the black hole's gravitational field.
"This long-term program has reaped many scientific rewards, and due to a combination of the spacecraft's flexibility and the sensitivity of its XRT, Swift is the only satellite that can carry out such a campaign," Neil Gehrels, the mission's principal investigator at NASA's Goddard Space Flight Center, said.
