Astronomers have learned to identify "unhealed scars" in the fabric of space-time.

Explosions and stellar mergers in space not only produce brilliant radiation; they also cause the very fabric of spacetime to "tremble." This effect is generated by the gravity of objects undergoing dramatic events. This phenomenon is known as "gravitational waves." Some of these waves never fade away, thus preserving the memory of countless "dead" stars throughout the Universe. Although this memory is challenging to detect, astronomers have managed to find a way to recognize it.

2024-12-20 10:01:19https://naked-science.ru/article/astronomy/astronomy-nauchilis-raspo

Gravitational waves spread out from their massive sources like ripples on water from a stone thrown into it. This stone can be represented by two neutron stars or black holes: as they "dance" around a common center of mass, their gravitational interaction creates a strong "ripple" in spacetime. The dance culminates in a complete merger, which generates the most intense gravitational waves. These are the waves currently being detected in space using specialized detectors.

However, there are gravitational waves that have yet to be detected because they are less distinct and have lower amplitudes, meaning they are significantly weaker. Such "ripples" occur at the moment when a neutron star or a black hole first appears—during a supernova explosion.

To remind you, a supernova is a "dying" very massive star. Its outer shell is expelled into the surrounding space during the explosion, while the core collapses and becomes one of two things: a neutron star or a black hole.

The most intriguing aspect is that these events not only cause a temporary strong disturbance in the fabric of the Universe—but very weak waves also persist as a "memory" of the great star forever. This phenomenon is called gravitational-wave memory. It was predicted by Einstein's General Theory of Relativity, just like the waves themselves. If it were possible to detect this memory effect, it would not only reaffirm the great physicist's calculations but also allow us to locate and study the sources of these "historical witnesses" of the Universe.

In a recent article for the journal Physical Review Letters, astrophysicists from the USA, Sweden, and Poland discussed a new method they developed to read the gravitational-wave memory of the Universe. They simulated the "death" of three stars that had masses of nearly 10, 15, and 25 solar masses during their "lifetime." As a result, they managed to create a fairly accurate picture of the nature of the gravitational waves that should arise at the moment of their core collapse.

It turned out that the temporal oscillations lasted for more than a second, which is quite significant: the gravitational ripples from stellar mergers last only fractions of a second. The eternal memory of a supernova remains due to the unique neutrino emission at the moment of the explosion and the uneven propagation of the shock wave, the researchers explained.

According to their calculations, it is now possible to meticulously compare various "patterns" of different gravitational waves with real data from detectors and thus find the everlasting "wounds" in the Universe left by exploding stars. In any case, the indelible consequences of the "death" of a star with a mass of 25 suns can be observed within a radius of about 30,000 light-years around us.

At the same time, it's worth mentioning that in a recently published monograph by physicist Nikolai Gorkyavyy, it is shown that very large black holes can "capture" gravitational waves, increasing their mass by the same amount that objects, which once emitted that gravitational wave, lost. In other words, some of the gravitational waves that the authors of the new study suggest searching for will, over time, be absorbed by black holes and gradually "erased."