Researcher to explain why matter-sucking presence exists in the cosmos

Wed, 10/31/2012 - 10:45pm

Images

Observations with Chandra (lower left image) and other X-ray observatories confirmed that a powerful X-ray outburst had occurred in the center of RX J1242-11, which appears normal in a ground-based optical image (lower right, with the white circle defining the location of the Chandra image). This X-ray outburst, one of the most powerful ever detected in a galaxy, is evidence for the catastrophic destruction of a star that wandered too close to a supermassive black hole. The illustration (top) shows how, after a close encounter with another star, the doomed star (orange circle) takes a path toward the giant black hole where the black hole's enormous gravity stretches the star until it is torn apart. Only a few percent of the disrupted star's mass (indicated by the white stream) is swallowed by the black hole, while the rest is flung away into the surrounding galaxy.

LOGAN — Our sun, if it were to reach the end of its life, go supernova, and collapse in on itself, could form a dense, sucking black hole with a diameter about the size of Logan.

Not that anyone would be around to fret over city boundaries in the wake of a stellar explosion, of course, or survive the billions of years into the future to witness the cosmic event.

Still, black holes are the subject of serious celestial study and intense public interest. And Pablo Laguna, a professor and the director of Georgia Tech’s Center for Relativistic Astrophysics, will do his best on Friday to satisfy public interest when he talks at Utah State University.

“I will explain to the general public what the objects are, and why we know they are present in the universe,” Laguna said. “Black holes have attracted the interest of the public. You have movies that feature these objects, and TV shows like ‘Star Trek.’ Astronomers believe there is very strong evidence black holes exist in the cosmos.”

NASA, the National Aeronautics and Space Administration (www.nasa.gov), describes a black hole as a place in space where gravity pulls so much that even light cannot get out. Because no light can get out, people can’t see black holes. Scientists discovered black holes by watching the behavior of nearby stars, as they were torn apart and disappeared.

“I will explain the characteristics of black holes and explain why these objects are so exotic,” Laguna said. “I will present a few examples, and people will be convinced they are there.

“The case that is more compelling is there is one in our own Milky Way galaxy. Observations show we have a black hole that has the mass a few million times that of the sun in our solar system.”

NASA’s Swift satellite recently detected a rising tide of high-energy X-rays from a source toward the center of our Milky Way galaxy. The outburst, produced by a rare X-ray nova, announced the presence of a previously unknown stellar-mass black hole, according to information from NASA.

“Bright X-ray novae are so rare that they’re essentially once-a-mission events and this is the first one Swift has seen,” Neil Gehrels, the mission’s principal investigator, said, in an Oct. 5 announcement by NASA. “This is really something we’ve been waiting for.”

Laguna said the newly detected black hole is far too distant to threaten Earth.

As part of his presentation, Laguna will also discuss Einstein’s theory of general relativity, and will show slides to illustrate black hole research from around the world.

“I’m going to give everyone a 30-second course in general relativity,” he said. Laguna also will talk briefly about his career, offering advice to any science students who might want to follow a similar path.