Astronomers and physicists say they've used supercomputers to help predict what happens when a supermassive black hole in the center of a galaxy swallows an approaching star in a giant "cosmic slurp."
A flash of bright light in a galaxy's center us usually a clue that its black hole has just taken advantage of such a cosmic meal, they say.
However, the scientists say, among the many billions of distant galaxies in the universe such an event would be difficult to spot, and even if seen might be difficult to distinguish from other galactic events such as supernovas.
"Black holes by themselves do not emit light," says physics Professor Tamara Bogdanovic at the Georgia Institute of Technology. "Our best chance to discover them in distant galaxies is if they interact with stars and gas that are around them."
With the ability, courtesy of bigger and better telescopes, to continuously monitor a vast number of galaxies, scientists say they've seen some previously inactive galaxies suddenly lighting up brightly at their exact centers.
"This flare of light was found to have a characteristic behavior as a function of time," Bogdanovic says. "It starts very bright and its luminosity then decreases in time in a particular way. Astronomers have identified those as galaxies where a central black hole just disrupted and 'ate' a star.
"It's like a black hole putting up a sign that says: 'Here I am.' "
Using supercomputers like the National Institute for Computational Sciences' Kraken and the Stampede system at the University of Texas, Austin, Bogdanovic and her study collaborators have successfully modeled the dynamics of such super powerful occurrences and their behavior with numerical simulations.
The researchers say they hope their work will lead to the ability to predict an observational signature expected when a black hole devours a star, an event also known to astrophycists as a "tidal disruption."
Such events are very rare cosmic happenings, they say, estimating a galaxy like our Milky Way disrupts a star just once in every 10,000 years.
Just a few dozen of the characteristic signatures considered candidates to be tidal disruptions have been observed to date, but with more astronomical surveys coming on line, Bogdanovic says she believes the number of candidates will increase dramatically.
"As opposed to a few dozen that have been found over the past 10 years, now imagine hundreds per year -- that's a huge difference!" she said. "It means that we will be able to build a varied sample of stars of different types being disrupted by supermassive black holes."
That could greatly advance our understanding of black holes and the stars that fall victim to them, they researchers say.
The researchers have submitted a paper on their findings to the Astrophysical Journal.
