Searching the Heavens with Supercomputing

The 1993 Nobel Prize in Physics recognized
Joseph H. Taylor and Russell A. Hulse, both now physicists at Princeton, for their discovery in 1974 of the first binary pulsar. This unique phenomenon, two stars orbiting each other -- one of them giving off regular radio-frequency "beeps" -- has been important as a deep space proving ground for Einstein's general theory of relativity.

Since the 1974 discovery, Taylor has continued searching the heavens for pulsars. As he and Hulse did in 1974, his research group at Princeton uses the 1,000 foot radio telescope at Arecibo, Puerto Rico, the largest and most sensitive bucket in the world for catching radio waves from space. What's different in the 1990s, however, is supercomputing. "What we are doing at Pittsburgh," says Taylor, "is a 1990s version of a pulsar survey, with many of the same goals as the work that made the interesting discovery 20 years ago. We're looking for previously unknown pulsars that statistically we know are out there, but we don't know where they are in the sky."

With the CRAY C90, Taylor's group can sift the data they collect at Arecibo with far greater sensitivity and efficiency than was possible 20 years ago, and this computing power is yielding a significant payoff in the discovery of pulsars. In particular, supercomputing makes it feasible to search for "millisecond pulsars," pulsars with very fast rotation periods (thus more "beeps" per second). "In a sense," says Taylor, "the first millisecond pulsar was the binary pulsar we found in 1974. Although that had a period of 59 milliseconds, it was the first of the genre. More recent ones found in the 80s have periods all the way down to 1.5 milliseconds. We would never have seen one of those with the computing equipment we had in 1974."

In three years of supercomputing at Pittsburgh, Taylor's group has discovered 20 previously unknown pulsars, including five of the superfast variety. Only about 50 millisecond pulsars are known, and 30 of these are in distant globular star clusters, where other stars' gravitational fields can interfere with precision measurements of the pulsar. Much more valuable for experiments in relativity are "field" millisecond pulsars -- outside of clusters. Only 20 of these are known, and five were discovered by Taylor's group using supercomputing at Pittsburgh.

Researcher: Joseph H. Taylor, Princeton University
Hardware: CRAY Y-MP C90
Software: User developed code.
Keywords: astrophysics, pulsar, binary pulsar, general relativity, gravity waves, pattern recognition, gravity radiation, neutron star, stellar astronomy.

Related Material on the Web:
PSC News Release about this research.
Projects in Scientific Computing, PSC's annual research report.

References, Acknowledgements, & Credits