A team of astrophysicists, led by Elias Most from Caltech, has modeled the milliseconds preceding the destruction of a neutron star by a black hole. Their work, published in
The Astrophysical Journal Letters, describes how the star's surface cracks under the effect of intense gravity.
The simulations show that 'starquakes' generate magnetic waves, converted into fast radio bursts. These signals could be detected by Caltech's future radio telescope network in Nevada. Elias Most explains that these waves are an acoustic signature of stellar destruction.
The study also predicts the emission of colossal shock waves during the star's final disappearance. Co-author Katerina Chatziioannou emphasizes that this simulation is the first to incorporate all the physics involved in this process.
A hypothetical object, the black hole pulsar, could briefly form during this process. Elias Most describes this phenomenon as a traditional pulsar, but powered by the black hole as it absorbs the neutron star.
The calculations were made possible by the Perlmutter supercomputer, equipped with graphics processors. Elias Most specifies that this computing power was essential to accurately model these extreme events.
How can a black hole produce radio waves?
When a black hole tears apart a neutron star, it generates disturbances in the star's magnetic field. These disturbances create Alfvén waves, which transform into detectable radio waves.
This process is similar to that observed in pulsars, where the intense magnetic field of a rotating neutron star produces beams of radio waves. However, in the case of a black hole, the phenomenon is much more violent and short-lived.
The resulting fast radio bursts (FRBs) are among the most energetic signals in the Universe. Their detection could provide valuable clues about the extreme conditions near black holes.
What is a black hole pulsar?
A black hole pulsar is a hypothetical object that would temporarily form during the absorption of a neutron star by a black hole. It combines the properties of a pulsar and a black hole.
During this process, the black hole drags the neutron star's magnetic field, creating a rotational effect similar to that of a pulsar. This rotation produces jets of particles and radiation.
Although this state is very ephemeral, it could emit distinctive signals, such as X-ray or gamma-ray bursts. These emissions would allow astronomers to identify such events in the Universe.