An international team of scientists including University of British
Columbia 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
puzzled scientists and 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 to 'correct' for the shifts.
"Humanity's best clocks all need corrections, perhaps for the
effects of changing temperature, atmospheric pressure, humidity or
local magnetic field," says Lyne. "Here, we have found a potential
means of correcting an astrophysical clock."
The findings were reported today in 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, or tick, 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."
The scientists made their breakthrough using the 76-m Lovell radio
telescope at the University of Manchester's Jodrell Bank
Observatory. "These exciting results were only possible because of
the quality and duration of the unique Lovell telescope pulsar
timing database," says Ben Stappers of the University of
Manchester.
As stated by Professor Michael Kramer of the Max Planck Institute
for Radioastronomy and the University of Manchester: "These results
give a completely new insight into the extreme conditions near
neutron stars and also offer the potential for improving our
already very precise experiments in gravitation."
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University of British Columbia: http://www.ubc.ca Thanks to
University of British Columbia for this article.