The Care and Feeding of Black Hole Sagittarius A

New observations from the GRAVITY and SINFONI instrument on the Very Large Telescope have given us unprecedented observations of material falling into the supermassive black hole at the center of the Milky Way Galaxy.

7720 Views | Published on 9th Nov, 2018

Hiding in the center of our Milky Way Galaxy is dark behemoth that defies our physics. Lying here, behind thick curtains of interstellar gas, dust and ice, is a well of gravity exceeding the gravitational pull of over four million stars. Astronomers call it a Sagitarrius A Star, a supermassive black hole.

Travelling from our home to this deep, dark pit, along the way, we pass by millions of stars, nebulae and stellar nurseries. A, intergalactic journey of some 26,700 light years.

We are travelling to a very strange place. Once we’ve pierced the galactic center’s veil blocking most radiation from reaching us by looking in infrared light, we begin to see with new and sensitive instruments a view of our galactic center like we’ve never seen before.

The first thing we can see are the stars orbiting this gravitational beast. The close ones fly around in unstable orbits, while others gently flow in free fall. Some of these stars, and one in particular called S2, are getting very close to the black hole.

S2 is orbiting Sag A star once every 16 years and at close approach, is at a perilous distance of only 18 billion kilometers. At this distance, S2 is travelling greater than 25 million kilometers per hour.

As amazing as watching these stars orbit Sag A star is, we can now look even closer, Using infrared telescopes never before brought to bear on this region operated the European Southern Observatory, we can also see something astonishing. Behind the orbiting stars lies a gas cloud, a stream of gas and dust, and it was captured falling into the Sagitarius A star as it happened.

For the first time, we can see a belt of gas falling into a black hole. Live.

Three flares were observed by the GRAVTY and SINFONI instruments on the Very Large Telescope. These three flares were infrared radiation given off as a knot of infalling gas trapped by the black hole fell in at over 30 percent the speed of light.

What isn’t clear is if these flares on one knot of gas seen three times, or three different knots of infalling material.

The supermassive black hole lying at the center of the milky way is a very strange place. The gravity pull from sag a star is unfathomable. As we get closer, the stronger the pull gets until a point of no return is reached. This is the event horizon.

Beyond it, Newton, Einstein, quantum mechanics, all of it, ceases to help us. These robust laws of nature no longer apply. Beyond the point of no return lies a singularity - a point of infinite density and zero volume, none of our tools equip us to help our understanding here. Does this mean we can never know for certain what lies beyond the event horizon?

One thing we can know for certain, with these new observations, there is now little doubt that there is in fact a supermassive black hole at the center of our galaxy.

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