An artist’s impression of a gamma-ray burst powered by a neutron star. Credit: Nuria Jordana-Mitjans

An international collaboration led out of the University of Bath has reported early measurements of a short-duration gamma-ray burst that challenge the standard paradigm for these phenomena. The source, GRB 180618A, was observed with space-and ground-based telescopes to construct a time sequence of emission from gamma-ray through optical wavelengths.

Observations with the Large Binocular Telescope obtained by LBTO and INAF astronomers were used to locate the galaxy where the transient event occurred. Deep-field observations from the Large Binocular Cameras and high-precision spectroscopic data from the Multi-Object Double Spectrographs revealed a galactic trio 10.6 billion light years away. Further examination of the LBT data indicated that the GRB exploded at the outskirts of one of these galaxies.

Analysis of the measured GRB emission points to an origin from a wind nebula powered by a young, highly magnetized neutron star, known as a magnetar. Previous studies of short GRBs implicated the merger of a binary pair of neutron stars that form a black hole as the source of energy driving the explosion. The new results also point to the merger of a neutron star binary as the precipitating event, but with a product that is itself a massive neutron star, accompanied by a release of gravitational and magnetic energy. The conclusion is that at least two types of merger processes underlie short-duration gamma-ray bursts.

The new results are reported in the published article by Jordana-Mitjans et al. (2022), Astrophys. Jour., 939, 106