![]() Every day, NICER could take a quick little look at this AGN, then go off and do something else.” “It’s this little washing machine bouncing around the ISS, and it can collect a ton of X-ray photons. “NICER is great because it’s so nimble,” Kara says. The team also watched the black hole daily with NASA’s NICER, a much smaller X-ray telescope, that is installed aboard the International Space Station, with detectors developed and built by researchers at MIT. Most of these telescopes were pointed at the the black hole periodically, for example recording observations for an entire day, every six months. The team used multiple telescopes to observe the black hole in the X-ray, optical, and ultraviolet wave bands. “Then they noticed that this run-of-the-mill AGN became suddenly bright, which got our attention, and we started pointing lots of other telescopes in lots of other wavelengths to look at it.” “This was an AGN that we sort of knew about, but it wasn’t very special,” Kara says. ![]() ASSASN observed that the object’s brightness jumped to about 40 times its normal luminosity. The survey recorded a flash from 1ES 1927+654, an active galactic nucleus, or AGN, that is a type of supermassive black hole with higher-than-normal brightness at the center of a galaxy. In March 2018, an unexpected burst lit up the view of ASSASN, the All-Sky Automated Survey for Super-Novae, that surveys the entire night sky for supernova activity. Co-authors from MIT include Ron Remillard, and Dheeraj Pasham. Kara and her co-authors, including lead author Claudio Ricci of Universidad Diego Portales in Santiago, Chile, have published their findings today in Astrophysical Journal Letters. “This will be really important to understanding how a black hole’s corona is heated and powered in the first place.” “This seems to be the first time we’ve ever seen a corona first of all disappear, but then also rebuild itself, and we’re watching this in real-time,” Kara says. In this way, in just a few months, the black hole was able to generate a new corona, almost back to its original luminosity. “But in this object, we saw it change by 10,000 over a year, and it even changed by a factor of 100 in eight hours, which is just totally unheard of and really mind-boggling.”įollowing the corona’s disappearance, astronomers continued to watch as the black hole began to slowly pull together material from its outer edges to reform its swirling accretion disk, which in turn began to spin up high-energy X-rays close to the black hole’s event horizon. “We expect that luminosity changes this big should vary on timescales of many thousands to millions of years,” says Erin Kara, assistant professor of physics at MIT. The result, as the astronomers observed, was a precipitous and surprising drop in the black hole’s brightness, by a factor of 10,000, in under just one year. ![]() Like a pebble tossed into a gearbox, the star may have ricocheted through the black hole’s disk of swirling material, causing everything in the vicinity, including the corona’s high-energy particles, to suddenly plummet into the black hole. The cause of this dramatic transformation is unclear, though the researchers guess that the source of the calamity may have been a star caught in the black hole’s gravitational pull. While a crown-encrusted virus has run roughshod over the world, another entirely different corona about 100 million light years from Earth has mysteriously disappeared.įor the first time, astronomers at MIT and elsewhere have watched as a supermassive black hole’s own corona, the ultrabright, billion-degree ring of high-energy particles that encircles a black hole’s event horizon, was abruptly destroyed. It seems the universe has an odd sense of humor.
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