Origin of gamma-ray bursts

Partly settled. Some of it is understood, some is still argued about.

Ginzburg, writing days after GRB 990123, called the cosmological origin of gamma-ray bursts one of astrophysics' great recent achievements (problem #29) while noting the central engine was still mysterious, and speculated about a hypernova connection. Since then, long-duration GRBs have been firmly linked to the core collapse of massive stars ('hypernovae'/collapsars, confirmed via associated supernovae such as GRB980425/SN1998bw and GRB030329/SN2003dh), while short-duration GRBs were spectacularly confirmed to arise from binary neutron-star mergers via the simultaneous gravitational-wave and gamma-ray detection of GW170817/GRB170817A in August 2017. Detailed jet physics and central-engine models are still actively researched.

For a few seconds, a single gamma-ray burst can outshine every other gamma-ray source in the observable universe combined, and in 2017 we finally watched one happen in gravitational waves and light at the same moment.

References

• What problems of physics and astrophysics seem now to be especially important and interesting (thirty years later, already on the verge of the XXI century)?, V L Ginzburg, Physics-Uspekhi 42 (4) 353-373, 1999
• Multi-messenger Observations of a Binary Neutron Star Merger, B. P. Abbott et al., The Astrophysical Journal Letters 848, L12, 2017
• An unusual supernova in the error box of the gamma-ray burst of 25 April 1998, T. J. Galama et al., Nature 395, 670, 1998