A 164-day period in γ-ray bursts from GBS0526-66

The γ-ray burst of GBS0526-66 is the brightest burst on record (5 March 1979) and one of only two from which recurrent bursts have been observed. The authors have found evidence for a pattern in the recurrence times of these bursts, showing an apparent period of 164 day, which suggests reflects periodic accretion to a neutron star from an eccentric (e approx. 0.9) binary companion. It is proposed that this system drives two types of bursts: (1) the relatively frequent, weak, recurrent bursts produced by either magnetospheric gating, or thermonuclear runaway, of periodically accreting matter around the neutron star, and (2) the much rarer intense bursts, like that of 5 March 1979, produced by tidally-triggered star quakes. (author)