Unprecedented gamma-ray burst explained by long-lived jet

Last year, Northwestern University researchers uncovered new observational evidence that long gamma-ray bursts (GRBs) can result from the merger of a neutron star with another compact object (either another neutron star or black hole) — a finding that was previously believed to be impossible.

Now, another Northwestern team offers a potential explanation for what generated the unprecedented and incredibly luminous burst of light. After developing the first numerical simulation that follows the jet evolution in a black hole-neutron star merger out to large distances, the astrophysicists discovered that the post-merger black hole can launch jets of material from the swallowed neutron star.

But the key ingredients are the mass of the violent whirlpool of gas (or accretion disk) surrounding the black hole and strength of the disk’s magnetic field. In massive disks, when the magnetic field is strong, the black hole launches a short-duration jet that is much brighter than anything ever seen in observations. When the massive disk has a weaker magnetic field, however, the black hole launches a jet with the same luminosity and long duration as the mysterious GRB (dubbed GRB211211A) spotted in 2021 and reported in 2022.

Not only does the new discovery help explain the origins of long GRBs, it also gives insight into the nature and physics of black holes, their magnetic fields and accretion disks.

Read the full CIERA news story here.

Credit: Ore Gottlieb/Danat Issa/Alexander Tchekhovskoy/CIERA/Northwestern

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