Primary black holes are considered as possible candidates for the particles that make up dark matter. It is believed that because of Hawking radiation, they cannot be smaller than a certain size. However, scientists have recently suggested that this is not the case.
Primary black holes
Japanese scientists have recently hypothesized that the mysterious dark matter is actually made up of primary black holes. What this form of matter represents is still unknown, because it does not interact with other matter in any way other than gravitational influence.
However, they stated quite reasonably that if dark matter consisted of axions, sterile neutrinos, or other exotic but still quite ordinary particles, they should have been produced in Earth’s boosters sooner or later. But no progress is seen in this direction, making the theory that dark matter is made up of primary black holes more likely.
These exotic objects were born at the dawn of the Universe due to the collapse of density regions and theoretically they could have any mass at that time. However, this does not mean that all of them should have survived to our time.
There is a phenomenon called Hawking radiation. It represents the birth of particles near the event horizon, causing the black hole to steadily lose mass until it disappears completely. As a result, among the primary black holes, only those with masses greater than a billion kilograms should have survived to the present day.
How black holes survive billions of years
A billion kilograms isn’t very much by cosmic standards. However, if dark matter only consists of such massive objects, then we would also have to find them by the gravitational influence they provide. But we don’t see that either.
This whole situation is trying to be remedied by a new study. Back in 2018, Georgian physicist Gia Dvali suggested that there was a mechanism that suppressed Hawking radiation. He viewed a black hole as a cluster of gravitons and concluded that there must be a phenomenon he called a “memory burden.” The very information absorbed by the black hole must resist evaporation.
It was on this assumption that the Japanese scientists based their work. They concluded that the modern universe may have preserved primary black holes with masses of less than 10 million kilograms. According to them, during the merger, such objects will emit gravitational waves, which will be able to record future space observatories — in particular, LISA (Laser Interferometer Space Antenna) and DECIGO (Deci-hertz Interferometer Gravitational-wave Observatory).
According to phys.org
