The Aftermath of a Neutron Star Collision


Editor’s note: AAS Nova is on vacation until 2 November. Normal posting will resume at that time; in the meantime, we’ll be taking this opportunity to look at a few interesting AAS journal articles that have recently been in the news or drawn attention.

The question of what happens after two neutron stars collide is still an open one — thrown into the spotlight in recent years with the detection of a gravitational-wave signal coincident with electromagnetic radiation from the neutron-star collision GW170817. Scientists are actively working to improve models of this process, and the latest comes from a team led by Philipp Mösta (University of Amsterdam). The authors’ 3D models show what might happen to a post-collision remnant — a hypermassive neutron star — as it evolves over time, gaining magnetic field strength and launching dramatic, relativistic jets and neutron-rich winds. The simulations show how a burst of gamma rays can be produced, as well as heavy elements like gold, all nicely matching observations of the 2017 merger.

Check out the video below to watch the authors’ simulated remnant (and its magnetic field lines) evolve for yourself.

Original article: “A Magnetar Engine for Short GRBs and Kilonovae,” Philipp Mösta et al 2020 ApJL 901 L37. doi:10.3847/2041-8213/abb6ef
NOVA press release: Improved model shows gamma rays and gold at merging neutron stars