Speedy, yet slower: The Crab Pulsar, a city-sized, magnetised neutron star spinning 30 times a second, lies at the center of this composite image of the Crab Nebula. The spectacular picture combines optical data (red) from the Hubble Space Telescope and X-ray images (blue) from the Chandra Observatory.
Credit: J. Hester (ASU) et al., CXC, HST, NASA
A perfectly smooth neutron star will not generate gravitational waves as it spins, said the researchers, but the situation changes if its shape is distorted. They reasoned that gravitational waves would have been detectable even if the star were deformed by just a few metres.
"The Crab neutron star is relatively young and therefore expected to be less symmetrical than most, which means it could generate more gravitational waves," said Woan.
"Eagerly awaited results"
However, the scenario that gravitational waves significantly brake the Crab pulsar has been disproved by his team's new analysis.
Using published data about the pulsar's rotation rate from the U.K.'s Jodrell Bank Observatory, LIGO scientists monitored the star from November 2005 to August 2006. The analysis revealed no signs of gravitational waves. But, said the scientists, this result is itself important because it provides information about the pulsar and its structure.
"The physics world has been waiting eagerly for scientific results from LIGO," commented Joseph Taylor, an astrophysicist at Princeton University in New Jersey, U.S., and winner of a Nobel Prize for the indirect detection of gravitational waves.
"It is exciting that we now know something concrete about how nearly spherical a neutron star must be, and we have definite limits on the strength of its internal magnetic field," he said.
The LIGO project, which is funded by the U.S. National Science Foundation, was designed and is operated by the California Institute of Technology and the Massachusetts Institute of Technology for the purpose of detecting gravitational waves. Research is carried out by the LIGO Scientific Collaboration, a group of 600 scientists at universities in 12 different countries.
with the University of Florida and the California Institute of Technology.
