University of British Columbia via EurekAlert | 24 June 2010
Cosmic clocks hold the key to the secrets of the UniverseAn 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.
University of Manchester | Jodrell Bank Centre for Astrophysics | 24 June 2010
Astronomers making good time: Correcting for rotational instabilities of pulsars, the most precise clocks in the UniverseAn international team of scientists have developed a promising new technique which could turn pulsars - superb natural cosmic clocks - into even more accurate time-keepers.
This important advance, led by scientists at The University of Manchester and appearing today (June 24th) in the journal Science Express, could improve the search for gravitational waves and help studies into the origins of the universe.
The direct discovery of gravitational waves, which pass over cosmic clocks and cause them to change, could allow scientists to study violent events such as the merging of super-massive black holes and help understand the universe shortly after its formation in the Big Bang.
The scientists made their breakthrough using decades-long observations from the 76-m Lovell radio telescope at The University of Manchester's Jodrell Bank Observatory to track the radio signals of extreme stars known as pulsars.
Pulsars are spinning collapsed stars which have been studied in great detail since their discovery in 1967. The extremely stable rotation of these cosmic fly-wheels has previously led to the discovery of the first planets orbiting other stars and provided stringent tests for theories of gravity that shape the Universe.
However, this rotational stability is not perfect and, until now, slight irregularities in their spin have significantly reduced their usefulness as precision tools.
The team, led by the University of Manchester's Professor Andrew Lyne, has used observations from the Lovell telescope to explain these variations and to demonstrate a method by which they may be corrected.
Max Planck Institute for Radioastronomy | 24 June 2010
Switched Magnetospheric Regulation of Pulsar Spin-DownAn international team of astronomers, including Michael Kramer from the Max-Planck-Institut für Radioastronomie (Bonn, Germany) has studied the behaviour of natural cosmic clocks and discovered a way to potentially turn them into the best time keepers in the Universe. The scientists made their breakthrough using decade-long observations from the 76-m Lovell radio telescope at the University of Manchester's Jodrell Bank Observatory to track the radio signals of an extreme type of star known as a pulsars. This new understanding of pulsar spin-down could improve the chances to use the fastest spinning pulsars in order to make the first direct detection of ripples, known as gravitational waves, in the fabric of space time.
Radio pulsars have been studied in detail since their discovery in 1967 and their exquisite rotational stability has led to the discovery of the first extra-Solar planets and provided tests for our theories of the Universe. However, the rotational stability is not perfect and, until now, slight irregularities in their rotation has significantly reduced their usefulness as precision tools.
The team, led by Professor Andrew Lyne, have used observations from the Lovell telescope to explain these variations and to demonstrate a method by which they may be corrected. Professor Lyne explains: "Mankind's best clocks all need corrections, perhaps for the effects of changing temperature, atmospheric pressure, humidity or local magnetic field. Here, we have found a potential means of correcting an astrophysical clock".
The rate at which all pulsars spin is known to be decreasing very slowly. What the team has found is that the deviations arise because there are actually two spin-down rates and not one, and that the pulsar switches between them, abruptly and rather unpredictably. Dr George Hobbs describes the team's second vital discovery "that these changes are associated with a change in the shape of the pulse, or tick, emitted by the pulsar. 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."
As stated by Professor Michael Kramer: "These results give a completely new insight into the extreme conditions near neutron stars and offer the potential for improving our already very precise experiments in gravitation". Michael Kramer, director at the Max-Planck-Institut für Radioastronomie and head of the research group "Fundamental Physics in Radio Astronomy" is this years recipient of the research award of the Berlin-Brandenburg Academy of Sciences for his contributions to the research of neutron stars.
It is hoped that this new understanding of pulsar spin-down will improve the chances that the fastest spinning pulsars will be used to make the first direct detection of ripples, known as gravitational waves, in the fabric of space time. As reported by Professor Ingrid Stairs "Many observatories around the World are attempting to use pulsars in order to detect the gravitational waves that are expected to be created by supermassive binary black holes in the Universe. 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."
- Science Express | 24 June 2010 | DOI: 10.1126/science.1186683