Our galaxy’s supermassive black hole is acting weirder than normal

The black hole often flickers, but outbursts are incredibly rare.

The supermassive black hole at the center of our galaxy has become unexpectedly active, with astronomers generally puzzled as to why Sagittarius A* has suddenly lit up with extreme brightness.

Like many galaxies, our own Milky Way is believed to revolve around a supermassive black hole.

"The black hole was so bright I at first mistook it for the star S0-2, because I had never seen Sagittarius A* that bright", said Tuan Do, an astronomer of the University of California, Los Angeles.

Sagittarius A*-the Milky Way's central black hole-is normally quite subdued, with low levels of activity recorded over years.

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S0-2 has been spotted a mere 17 light-hours away from the center as recently as previous year, and it's possible that the star's close relationship with the black hole has led to an increase in gas being swallowed up by it, which may have led to a burst of radiation visible using infrared. Their findings so far are now in press with The Astrophysical Journal Letters.

Do and his team took observations of the galactic centre using the WM Keck Observatory in Hawaii over four nights earlier this year. Black holes themselves don't emit any radiation that can be detected by our current instruments, but the stuff nearby does when the black hole's gravitational forces generate enormous friction, in turn producing radiation. Passing stars, orbiting around the black hole because of its incredible gravity, can end up donating their material to the disk as they graze by those forces, and it's theorized that this Sgr A* activity is because of an extra-large meal from one such pass. But no one was aware that anything was drawing close enough to be swallowed by the black hole. The team points to two possibilities. A huge dust cloud known as G2 also came extremely close to Sagittarius A*recently. Last year, it made its closest approach, coming within 17 light-hours of the black hole. There were no cosmic fireworks at the time, but we could be seeing a delayed reaction. The visualization shows S0-2's close encounter with the black hole, as over a dozen other stars encircle Sagittarius A*. "Additional multi-wavelength observations will be necessary to both monitor Sagittarius A* for potential state changes and to constrain the physical processes responsible for its current variability".

Do told ScienceAlert they are now waiting for data from other telescopes, including NASA's Spitzer and Chandra, to better understand what might have happened with Sagittarius A*.

Luckily, there are plenty of sources for extra data to help fathom the cause of the change.

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