Binary pulsar

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A binary pulsar is a pulsar with a binary companion, often another pulsar, white dwarf or neutron star. They are one of the few objects which allow physicists to test general relativity in the case of a strong gravitational field. Although the binary companion to the pulsar is usually difficult or impossible to observe, the timing of the pulses from the pulsar can be measured with extraordinary accuracy by radio telescopes. A relatively simple 10-parameter model incorporating information about the pulsar timing, the Keplerian orbits and three post-Keplerian corrections (the rate of periastron advance, a factor for gravitational redshift and a rate of change of the orbital period from gravitational radiation) is sufficient to completely model the pulsar timing. Binary pulsar timing has thus indirectly confirmed the existence of gravitational radiation and verified Einstein's general theory of relativity in a previously unknown regime.

The first binary pulsar, PSR 1913+16 or the "Hulse-Taylor binary pulsar" was discovered in 1974 at Arecibo by Joseph Hooton Taylor, Jr. and Russell Hulse, for which they won the 1993 Nobel Prize in Physics. Pulses from this system have been tracked, without glitches, to within 15 μs since its discovery.