Astronomers have proposed searching for gravitational waves from a new type of cosmic source – the explosion of supermassive stars. Previously, these waves were picked up only by binary systems of black holes and neutron stars. Heavy stars that collapse into a black hole at the end of their life explode asymmetrically, so their signal can be received by the international detector LIGO, said study authors at a conference of the American Astronomical Society.
Until recently, gravitational waves, for the discovery of which the Nobel Prize in Physics was awarded in 2017, were recorded as coming only from binary objects in the universe – merging black holes or pairs of neutron stars . Gravitational waves generated by a single object have yet to be recorded, but scientists have speculated that it is possible.
In 2022, Russian media was informed by the 2017 Nobel Prize in Physics winner, American astrophysicist Kip Thorne, what gravitational wave signals from what new objects scientists will be able to receive with an increase in the sensitivity of LIGO-type detectors .
In their new study, physicists from Northwestern University, led by Or Gottlieb, have shown that scientists will soon be able to capture gravitational waves from completely unexpected sources – the shells of dying massive stars. Gottlieb and his colleagues performed sophisticated computer simulations of the gravitational collapse of massive stars. At the final stage of evolution, these stars collapse into a black hole, during which powerful jets of particles moving at near-light speeds can escape from the center of the star.
Scientists were able to simulate this process – from the onset of collapse to the expansion of the jet substance.
Initially, Gottlieb wanted to understand if the accretion disk around a newborn black hole could emit gravitational waves that could be recorded on Earth. “When I was calculating gravity waves near a black hole, I noticed another source that was violating my calculations – the shell,” Gottlieb said. “I tried to ignore it, but realized that was impossible. Then I realized that the shell is an interesting source of gravitational waves.
When the substance of the jets collides with the outer layers falling in the center of the star, peculiar bubbles, or cocoons, form around the jets, in which the hot gas and the remnants of the outer layers mix and disperse in different directions from the jet. As the bubble expands, its substance disrupts the space-time around it, causing gravitational waves to propagate.
According to the scientists, if gravitational waves from the expanding shells of these stars are generated, they will soon be able to register the LIGO detector, which is constantly being improved. Previously, astrophysicists have tried to capture waves from single sources such as gamma-ray bursts and supernovae, but scientists doubt LIGO is able to fix them.
“Jets and supernovae are high-energy explosions. But we can only detect high-frequency waves, coming from asymmetric explosions, Gottlieb explained. – Supernova explosions are spherical and symmetrical, and such explosions do not violate the balanced distribution of mass in stars, so gravitational waves are emitted. The bursts of gamma rays last for tens of seconds, so the frequencies are too low – below LIGO’s sensitivity.
For this reason, scientists ask observers to pay attention to the expanding shells of dying stars, which on the one hand can be asymmetrical, and on the other hand have high energies.
Read the Latest Ukraine War News on The Eastern Herald.
