Space + Flight


The High-Energy Particle Geyser at the Center of the Milky Way

Deep in the center of our galaxy, just 26,000 light-years from Earth, lies a supermassive black hole some 4 million solar masses large. Its name is Sagittarius A*, and we know its intense gravitational force has drawing stars, gas, and dust toward its event horizon. But much about this black hole—the nearest—remains a mystery, in part because cloudy curtain of stellar debris has obscured our view. For years, we’ve been trying to lift the veil.

Now, with the combined power of the Chandra X-ray Observatory, a space telescope, and the Very Large Array, a radio telescope in New Mexico, astronomers think they have the clearest glimpse yet of what’s happening at the murky center of the Milky Way. As Sagittarius A* draws matter toward its event horizon, it spins the debris with such force that only 1% of the matter within its grasp is thought to be pulled past the point of no return. The rest is deflected away by the angular momentum, forming the hazy curtain that has obstructed our view.

Sagitarrius A*, seen in this composite image as a bright purple spot of radio data just above an arc of blue x-ray data, appears to be spewing high-energy particles

Through that fog, though, astronomers using Chandra and the VLA have seen strong evidence of jets energetic particles pouring from Sagittarius A*, something they have long suspected. Here’s Clara Moskowitz, writing for Scientific American:

The x-ray photos show a wispy bright line of gas that is emitting x-ray light to one side of the black hole—perhaps indicating the jet itself—and the radio observations highlight a wall of gas that scientists think is a shock front created where the jet is slamming into a cloud, snow-plowing the gas into a clump.

Those results, coupled with the angle of the signals (the same as the spin axis the black hole), have scientists more convinced than ever that jets are pouring from Sagittarius A*. In a few years, we may get an even sharper picture when the nearby gas cloud G2, which has been closely orbiting the black hole, finally succumbs, providing even more matter and x-rays to light the center of the Milky Way.

Learn more about Sagittarius A* by watching “Monster of the Milky Way.”