(ORDO NEWS) — Using supercomputer simulations, for the first time, researchers have been able to recreate the entire collision process between a neutron star and a black hole.
In their work, they calculated the state of the system at the final stages of the orbital rendezvous, during the merger, as well as at the stage after the completion of the merger, at which, according to the data obtained, gamma-ray bursts can occur.
For their study, scientists led by Kota Hayashi of Kyoto University, Japan, chose two different model systems, consisting of a rotating black hole and a neutron star.
The masses of black holes were 5.4 and 8.1 solar masses, respectively, while the mass of a neutron star in both cases was 1.35 masses of our star.
These parameters were chosen based on the condition that the neutron star would be torn apart by tidal forces acting from the black hole.
“We got an idea of a process that lasts for only 1-2 seconds. However, during this seemingly not very long period of time, a large number of processes occur: the last orbital turns of the original bodies, the rupture of a neutron star by tidal forces, ejections of matter, the formation of an accretion disk around a newborn black hole, as well as a further eruption of matter in the form of jets, said co-author Masaru Shibata of the Max Planck Institute for Gravitational Physics in Potsdam, Germany.
“The study also showed that heavy elements, such as gold and platinum, may be present in the streams of erupted material.”
The simulation showed that during the merging process, the neutron star is torn apart by tidal forces. Approximately 80 percent of the neutron star’s matter falls into the black hole within a few milliseconds, causing the latter’s mass to increase by about one solar mass.
In the next approximately 10 milliseconds, the matter of the neutron star forms a one-armed spiral structure. Part of the matter that is part of the spiral arm is ejected from the system, while the rest (0.2-0.3 solar masses) forms an accretion disk around the black hole.
When this accretion disk falls onto the black hole after a collision, it results in the formation of a focused jet of electromagnetic radiation, which may be accompanied by a gamma-ray burst.
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