It’s a world that eats dog. Just two weeks ago, on May 3, astronomers reported spotting a star that was on its way to swallowing up one of its planets. Just two days ago, another team described Black holes ripping stars apart and consuming them in a process known as a tidal disturbance event, or TDE
Now an international group of astronomers is reporting that it is observing one of the most violent and energetic acts of cosmic cannibalism it has ever witnessed, perhaps the largest explosion yet seen in the history of the universe. Eight billion light-years from Earth, in the darkness beyond the constellation of Vulpicula, a black hole a billion times more massive than the Sun appears to be devouring a huge cloud of gas. study of the phenomenon Friday appeared in the Monthly Notices of the Royal Astronomical Society.
The study began on April 13, 2021, when the Zwicky Transit Facility, a small telescope that was busy searching for exploding stars, or supernovae, detected a bright flash that didn’t match expectations. Most supernovae fade after a few weeks; This one, known as the AT2021lwx, has persisted — and has continued to explode for three years now.
In fact, it turns out that the explosion was first detected a year ago by the Terrestrial Asteroid Collision Last Alert System, or ATLAS, a network of robotic telescopes in Hawaii, South Africa, and Chile. That was the actual beginning of the disaster. As it progressed, a global network of telescopes and satellites monitored it, measuring its emission across the electromagnetic spectrum, from high-energy X-rays to infrared.
“Most supernovae and tidal disruption events only last a couple of months before fading,” said Philip Wiseman, an astrophysicist at the University of Southampton and lead author of the new paper. “For something to be bright for over two years was immediately unusual.”
What happened? “We initially thought this glow might be the result of a black hole consuming a passing star,” said Matt Nicholl of Queen’s University Belfast, who helped analyze the ongoing outburst. “But our models showed that a black hole would have to swallow up to 15 times the mass of our Sun to remain bright for that long.”
The other idea was that it was an explosion from a quasar – energy pouring from the edge of a supermassive black hole at the heart of a galaxy. But there was no record of previous quasar activity at the site, nor was there any visible sign of a galaxy there.
Among the many unexpected explanations, Dr. Weizmann and his colleagues conclude, is that a black hole the size of a billion suns was enjoying a long feast on a massive cloud of gas. They encouraged colleagues to research similar events.
“AT2021lwx is an exceptional event that does not fit into any common category of transients,” Dr. Wiseman said in an email. With a total radiant energy equal to 100 supernovae, he added, “it is one of the brightest transiting objects ever discovered.”
A jolt for a jolt’s sake, that would put it in the company of colliding black holes. “The collision of black holes releases energy in gravitational waves at an extreme luminosity — 10 billion times more powerful than this explosion,” Dr. Wiseman wrote. “But this force only lasts for 20 milliseconds,” he said, adding that this explosion has been going on for years.
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