Chelsea Gohd / Astronomy.com
Scientists have finally confirmed that the massive object at the heart of our galaxy is, in fact, a supermassive black hole.
Researchers used the European Southern Observatory’s sensitive GRAVITY instrument on the Very Large Telescope (VLT) to observe infrared radiation flares coming from the accretion disc around Sagittarius A* — the massive object at the center of our galaxy. Scientists think that most galaxies have a supermassive black hole at their center, but they’d never before had the data and observations to prove it.
To measure the effects of gravity near to a black hole, scientists needed to observe an object actually traveling close to it. They found their mark in a small star called S2 whose orbit takes it deep within Sagittarius A*’s gravity well every 16 years. As they watched, they saw three bright flares traveling around the black hole’s event horizon at about 30 percent of the speed of light — around 216 million miles per hour.
Jesse Stone / Nautilus
What does the supermassive black hole at the center of the Milky Way look like? Early next year, we might find out. The Event Horizon Telescope—really a virtual telescope with an effective diameter of the Earth—has been pointing at Sagittarius A* for the last several years. Most researchers in the astrophysics community expect that its images, taken from telescopes all over the Earth, will show the telltale signs of a black hole: a bright swirl of light, produced by a disc of gases trapped in the black hole’s orbit, surrounding a black shadow at the center—the event horizon. This encloses the region of space where the black-hole singularity’s gravitational pull is too strong for light to escape.
But George Chapline, a physicist at the Lawrence Berkeley National Laboratory, doesn’t expect to see a black hole. He doesn’t believe they’re real. In 2005, he told Nature that “it’s a near certainty that black holes don’t exist” and—building on previous work he’d done with physics Nobel laureate Robert Laughlin—introduced an alternative model that he dubbed “dark energy stars.”