Mysterious ultrafast radio bursts, the nature of which remains a mystery to scientists, may arise from the explosions of exotic primordial black holes that existed in the early eras of the universe, according to an article published in the journal Nature Astronomy.
“Observations of the past ten years show that the universe is literally teeming with black holes of various types and masses, which can differ by nine orders of magnitude. According to the theory of relativity, black holes should be stable, but today theorists believe that they gradually “evaporate” under the influence of quantum effects,”writes Carlo Rovelli, an astrophysicist at the University of Toulon (France).
Classic black holes are collapsed stars whose mass exceeds the mass of the sun by 10 or more times. Modern physical theories predict that their lighter counterparts, the so-called primordial black holes, which arise due to the formation of especially dense large "balls" of dark matter, may exist in the Universe.
Such black holes, according to Rovelli, one of the founders of the controversial theory of loop quantum gravity, can not only slowly "evaporate" into space in the form of Hawking radiation, as a result of the formation of pairs of particles and antiparticles at their event horizon, but also as a result of direct quantum tunneling particles inside the singularity.
A similar version of the "evaporation" of a black hole, according to the astrophysicist, will be possible if primordial black holes comparable in mass to the Earth or other planets will in fact represent not the classical "Einstein" singularity, but a more exotic object - so called the Planck star.
By this word, scientists mean a special object of stellar mass that seeks to shrink into a point, but cannot do this due to the fact that its mass is not enough to overcome the special quantum effects that make its particles repel each other. They are similar in nature and principle of action to those forces that do not allow electrons to approach the nucleus of an atom and "fall" into it.
These forces make the "Planck stars" unstable in nature - immediately after they begin to shrink, quantum effects begin to destroy them, forcing particles of matter to leave their bowels through quantum tunneling. In fact, as the physicist explains, the black hole almost instantly turns into its kind of antipode, the white hole, and explodes with a power comparable to that of a typical supernova.
According to Rovelli, if we were inside such an object, then this process would most likely take a very short time, but "outside", thanks to the extremely strong time dilation in the vicinity of the primordial black hole, the traces of the explosion of Planck's star will be visible through millions of or tens of millions of years.
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This "delayed" explosion, as the calculations of the Italian astrophysicist show, should be the brightest in the millimeter part of the radio spectrum, approximately in the same part of it, where the mysterious fast radio flares were recorded, the unusual nature of which made scientists think about their artificial origin.
Testing this theory is easy enough, Rovelli said. The fact is that the "pattern" of the spectrum of flares generated by explosions of such black holes will depend in a special way on the distance at which the black hole was from the Earth. If FRB flares that have arisen at far and close distances from our planet have the same spectral differences that Rovelli's theory predicts, then his calculations will be confirmed.
