Reviewed by Lexie CornerAug 7 2024
According to a study published in The Astrophysical Journal, scientists used powerful supercomputer simulations to investigate the interior structure of a new celestial object called remnants and the cooling process, which is predominantly driven by neutrino emissions.
False color plot showing the density of the mass in the equatorial (bottom) and meridional, or “southern” (top) planes of a neutron star merger remnant about 100 milliseconds after the merger. Image Credit: David Radice
Following the collision of neutron stars, a new celestial entity known as a remnant emerges, shrouded in mystery. Scientists are still trying to determine if it collapses into a black hole and how quickly this occurs.
The results indicate a fast-spinning ring of hot material surrounding a central object. Scientists predict that if these remnants avoid collapsing, they will discharge most of their intrinsic energy within seconds of their formation.
The Impact
By studying the merging of neutron stars in space, scientists can learn more about the behavior of nuclear matter under extreme conditions, which cannot be replicated on Earth. Nuclear matter, a hypothetical substance, consists of protons and neutrons bound together by a strong force.
A key interest for scientists is whether the pressure from this strong force can prevent the formation of black holes. This research focused on what happens when neutron stars merge but do not form black holes, specifically examining their first few minutes of existence.
This study provides a foundation for identifying astronomical signals that could shed light on the genesis of black holes and neutron stars.
Summary
Scientists at Pennsylvania State University have studied the interior structure of neutron star merger remnants using supercomputer simulations based on general-relativistic neutrino-radiation hydrodynamics. They also investigated the neutrino emission that occurs as the remnant cools.
The study utilized computational resources from Pennsylvania State University's Institute for Computational and Data Science, the Leibniz Supercomputing Center in Germany, and the Department of Energy's National Energy Research Scientific Computing Center.
According to the research, neutron star merger remnants consist of a central object holding the majority of the system’s mass and a rapidly rotating ring of hot matter, which contains a large fraction of the angular momentum but only a small fraction of the mass. Unlike most stars, the inner remnant has a higher surface temperature than its core, so convective plumes are not expected to form as the remnant cools by releasing neutrinos.
The Department of Energy's Office of Science, Nuclear Physics program funded the study, with additional support from the National Science Foundation and the European Union.
Journal Reference:
David, R., et. al. (2024) Ab-initio General-relativistic Neutrino-radiation Hydrodynamics Simulations of Long-lived Neutron Star Merger Remnants to Neutrino Cooling Timescales. The Astrophysical Journal. doi:10.3847/1538-4357/ad0235