Pulsar Timings Improved -- Better Clocks
An international team of scientists including UBC astronomer Ingrid Stairs has discovered a promising way to fine-tune pulsars into the best precision time-pieces in the Universe.
The discovery could give astronomers a new tool to study the powerful gravitational forces that shaped the universe.
Pulsars--incredibly fast spinning collapsed stars--have been studied in great detail since their discovery in 1967. The extremely stable rotation of these 'cosmic clocks' has enabled astronomers to discover the first planets orbiting other stars and provided stringent tests for theories of the Universe.
However, until now, slight irregularities in their spin have significantly reduced their usefulness as precision tools.
Astronomers have observed that pulsar spin rates slow very gradually over time. The team, led by the University of Manchester's Professor Andrew Lyne, used decades-worth of observations to determine that pulsars actually exhibit two different rates of spin change, not one as previously thought, and switch between them abruptly. The team also discovered that these variations are associated with changes in the pulsar's appearance that can be used "correct" for the shifts.
The findings were reported in 2010-06-24 issue of Science Express.
The discovery makes pulsars better tools for detecting gravitational waves--mysterious, powerful ripples which have not yet been directly observed, although widely believed to exist. The direct discovery of gravitational waves, which cause the distortion of space, could allow scientists to study the Universe shortly after the Big Bang and other violent events such as the merging of super-massive black holes.
"Many observatories around the world are attempting to use pulsars in order to detect the gravitational waves that are expected to be created by super-massive binary black holes in the Universe," says Stairs. "With our new technique we may be able to reveal the gravitational wave signals that are currently hidden because of the irregularities in the pulsar rotation."
"These changes are associated with a change in the shape of the pulse emitted by the pulsar," says George Hobbs of the Australia Telescope National Facility. "Because of this, precision measurements of the pulse shape at any particular time indicate exactly what the slowdown rate is and allow the calculation of a "correction". This significantly improves their properties as clocks."