Bruce Allen, Einstein@Home: hunting for neutron stars with gravitational and radio waves

Einstein@Home is a traditional citizen science project. Have 100,000 computers at any one time contacting project and looking for work. People join the project by joining website, download & install software, and then leave it alone. Get a screensaver (which is very pretty!), and when their computer is idle it is analysing data.

Physics experiment data. Not simulating, but taking real data about physical world and searching for very weak signals that reveal neutron stars – very compact, small start, 10km radius, which beams radio waves like a lighthouse. As beam passes by Earth you see a flash. Forms when an ordinary star burns all its fuel and collapses under gravity, electrons get crushed into the nucleus, combine with protons to form neutrons, which are 100x smaller than the original atom. They spin very quickly for same reason an ice skater spins faster when they pull in their arms.

Example, Crab Pulsar, formed 1054AD, spins 33 times per second. About 100m neutron stars in galaxy, but have found about 1900, mostly near us.

Einstein@Home uses gravitational waves to search for neutron stars sent out by the star. Detectors, built in last 20 years, made of mirrors hanging from wires, and when a gravitational wave comes along the mirrors swing a bit. That can be detected.

Also use data from Arecibo radio telescope in Puerto Rico. First discovery: 11 July 2010. Signal was followed up the next day and reconfirmed quickly.

Found a second radio pulsar, currently unpublished, appears to be a binary system, but not yet clear what the masses of the stars are.

Publicity of first discovery has been very inspiring for users and project team. New users jumped when the publicity happened, and the number of users leaving the software running continues increase.

Square Kilometer Array, which will come online in 2019 or later will produce so much data that distributed computing may be the only way to process it.