Solving The Mystery Of The Disappearing Quasar

Feb 23, 2016

Photo credit: Dana Berry/SkyWorks Digital; SDSS collaboration

By Joe Palca

If this were a Sherlock Holmes story, its title would surely be “The Case of the Disappearing Quasar.”

In this case, however, the mystery wasn’t solved by an aging Victorian-era detective, but by a young American astronomer at Penn State University named Jessie Runnoe and her colleagues. They study quasars, some of the brightest objects in the universe.

Quasars aren’t stars. “They’re the result of gas and material falling into a supermassive black hole,” Runnoe says. The gas heats up as it falls in, causing the region to glow brightly.

The case began early last year.

Runnoe and her colleagues were studying the properties of the light coming from quasars, something known as the quasar’s spectral signature. They wanted to know how the spectral signature changed over time

In January 2015, they decided to measure the spectrum of a quasar with the prosaic name J1011+5442. Its spectrum had been measured in 2003, and they decided it was time to look again.

“And when we went back to look, all of the spectral signatures we associate with a quasar were gone,” she says.

It seemed the quasar just disappeared.

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