BY DR EMILY BALDWIN
Posted: 24 March, 2009
First there was SETI@Home, now there is Einstein@Home, an initiative that calls on the general public to donate computational time to searching for gravitational wave data that could help detect new pulsars.
SETI@Home was launched in May 1999, and uses a screensaver package to analyse blocks of data recorded by the Arecibo Observatory, the largest single-aperture radio telescope on the planet, that could contain extraterrestrial radio signals. The concept was based on the fact that more computing power enables searches to cover greater frequency ranges with more sensitivity. The same applies to Einstein@Home, which also uses the Arecibo Observatory to search for radio pulsars, as well as the Laser Interferometer Gravitational Wave Observatory (LIGO) gravitational wave detector to search for gravitational waves.
Double pulsars are rare in the Universe, but the impressive computing power of Einstein@Home could help detect them. Image: John Rowe Animations.
Gravitational waves were first predicted by Einstein in 1916 as a consequence of his general theory of relativity, but have not yet been directly detected. They can be described as the ripples in the fabric of space and time that are produced by violent events in the distant Universe, such as the collision of two black holes or by the cores of supernova explosions. As these ripples propagate towards the Earth, they bring with them information about their violent origins and about the nature of gravity.
More than 200,000 volunteers have already signed up to the Einstein@Home initiative, and this week, Bruce Allen, Director of the Einstein@Home project, and Jim Cordes, Chair of the Arecibo PALFA (Pulsar Arecibo L-band Feed Array) Consortium, announced that the project is beginning to analyse data taken by the PALFA Consortium at the Arecibo Observatory in Puerto Rico.
“While our long-term goal is to detect gravitational waves, in the shorter term we hope to discover at least a few new radio pulsars per year, which should be a lot of fun for Einstein@Home participants and should also be very interesting for astronomers,” says Allen. “We expect that most of the project’s participants will be eager to do both types of searches.” Einstein@Home participants will automatically receive work for both the radio and gravitational-wave searches.
The Crab Nebula as seen from the ground (left) and its interior pulsar as seen by Hubble. The Crab Pulsar is a rapidly rotating neutron star. Image: Jeff Hester and Paul Scowen (Arizona State University) and NASA.
Radio pulsars are rapidly spinning neutron stars that emit a lighthouse-like beam of radio waves that bathe the Earth in radiation as frequently as 600 times per second. Radio
Einstein@Home will search Arecibo radio data to find binary systems consisting of the most extreme objects in the Universe: a spinning neutron star orbiting another neutron star or a black hole. Current searches of radio data lose sensitivity for orbital periods shorter than about 50 minutes. But the enormous
“Discovery of a pulsar orbiting a neutron star or black hole, with a sub-hour orbital period, would provide tremendous opportunities to test General Relativity and to estimate how often such binaries merge,” says Cordes. The mergers of such systems are among the rarest and most spectacular events in the Universe, emitting bursts of gravitational waves that current detectors might be able to detect, as well as gamma rays just before the merged stars collapse to form a black hole. “The Einstein@Home computing resources are a perfect complement to the data management systems at the Cornell Center for Advanced Computing and the other PALFA institutions.”