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

Rodiano Bonacci
Agosto 13, 2019

Sagittarius A*, the supermassive black hole located at the center of our galaxy, recently emitted a remarkably bright flash - 75 times brighter than black hole's normal glow, Newsweek reported Monday. That's the mass of materials - including gases and dusts - that are drawn to the black hole but don't make it past the event horizon. It is roughly twice the size of the record-holding black hole it displaced - the black hole at the centre of galaxy NGC 1277, which is ~11 times as wide as the orbit of Neptune around the sun. However, it became apparent over the course of about two and a half hours that the source was variable and was, in fact, Sagittarius A*. "I knew nearly right away there was probably something interesting going on with the black hole". The unusual brightening took place on May 13, and the team managed to capture it in a timelapse, two hours condensed down to a few seconds.

Massive jets propelling away from the black hole at the centre of Centaurus A galaxy 13 million light-years away.

The first frame - taken right at the beginning of the observation - is the brightest, which means Sgr A* could have been even brighter before they started observing, Do said.

The researchers think it's possible that the black hole ate up the stars surrounding it, or pushed them away.

Scientists say they weren't aware of anything travelling close enough to create that kind of friction, however.

"One of the possibilities", Do told ScienceAlert, "is that the star S0-2, when it passed close to the black hole past year, changed the way gas flows into the black hole, and so more gas is falling on it, leading it to become more variable".

In May of this year, UCLA's Tuan Do spotted an unusual pulse from Sagittarius A*.

Other teams and telescopes, such as Spitzer, Swift, Chandra, and ALMA, have also been observing Sagittarius A*. In the late 1990s and early 2000s, studies of objects near Sagittarius A* demonstrated it had a strong gravity explained best by a supermassive black hole. If it was a gas cloud, this proximity should have torn it to shreds, and parts of it devoured by the black hole - yet nothing happened.

Evidence of a black hole at the centre of our galaxy was first presented by physicist Karl Jansky in 1931, when he discovered radio waves coming from the region.

At just 26,000 light years from Earth, Sgr A* is one of very few black holes in the universe where we can actually witness the flow of matter nearby. These were also the same telescopes used to capture the iconic first photograph of a black hole's event horizon.

Supermassive black holes are common in the centers of galaxies and may generate the most energetic phenomena in the known universe. The ejection of matter allows this loss to occur.

The captured material needs to lose heat and angular momentum before being able to plunge into the black hole.

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