Using a previously abandoned mathematical model

Jun 19, 2007 14:23 GMT  ·  By

A group of researchers came up with a new, and in the same time old, method of searching for gravitational waves, using a mathematical model that hadn't be used for some time, in the hope of studying and accurately identifying an exotic kind of these gravitational waves.

The gravitational wave is a fluctuation in the curvature of spacetime which propagates as a wave, traveling outward from a moving object or system of objects and carrying energy. These waves are formed by binary star systems, where the two stars in the binary are white dwarfs, neutron stars, or black holes.

Dr. Lior Burko, an assistant physics professor at the University of Alabama in Huntsville (UAH), says that "This reopens an area of research that was closed several years ago."

He and Dr. Gaurav Khanna at the University of Massachusetts at Dartmouth published the results of a research on the subject, where they used some mathematical time-domain formulas that had been abandoned because they produced error rates of ten percent or more, compared to the more accurate frequency-domain formulae.

General relativity theory predicts that the gravitational waves form when an orbiting compact object changes speed, accelerating as it approaches the larger black hole and slowing as it moves away. The simplest example of a strong source of gravitational waves is a spinning neutron star with a small mountain on its surface.

The mountain's mass will cause curvature of the spacetime. Its movement will "stir up" spacetime, much like a paddle stirring up water. The waves will spread out through the Universe at the speed of light, never stopping or slowing down. "Just as an accelerating electric charge emits electromagnetic waves, so mass emits gravitational waves as the speed changes," Burko said.

Unfortunately, the major problem with the frequency-domain math is the fact that it doesn't work very well with objects that have an extremely elliptic orbit without wasting a lot of computer time (and still getting large errors). And objects in elliptic or parabolic orbits are reasonably common in astronomy, as stars and small black holes wander or are pulled into orbits around massive black holes.

Burko and Khanna found that they could use the old mathematical models with reasonable errors, thus providing a new way of calculating the gravitational waves.