The 1979 March 5 Gamma-Ray Transient: Was It a Classic Gamma-Ray Burst?

Abstract

The March 5th, 1979 gamma-ray transient has long been thought to be fundamentally different from the classic gamma-ray bursts (GRBs). It had recurrences, pulsations, and a soft spectral component unlike classic GRBs. With the exception of the soft component reported from the Konus experiment, the unusual characteristics of March 5th were detectable main peak differs markedly from the published Konus spectrum. Rather than being dominated by a soft component similar to that observed in the soft gamma repeaters (SGRs), the ICE-PVO spectrum appears to be consistent with a classic GRB spectrum, especially above 100 keV. We believe that, given the ICE-PVO spectral observations, the March 5th transient would have been classified as a classic GRB when it was discovered. The SGRs and GRBs could be consanguineous: high-velocity neutron stars initially produce SGR events (and, occasionally a GRB like March 5th) and when they are older and in the galactic corona, they go through a GRB phase. The March 5th event demonstrates that high-velocity neutron stars at distances of tens kpc are capable of producing events like classic GRBs.