Primal black holes the size of an atom, the true nature of dark matter?

Dark matter is an unknown type of matter that cannot be detected other than by its gravitational influence. It is more abundant in the cosmos than normal matter. It does not correspond to conventional black holes or to any other known class of astro. Some scientists have come to the conclusion that the identity of dark matter is that of a hypothetical class of black holes, created in the first moments of existence of the universe, as a direct consequence of the Big Bang, and that would have masses comparable to those of an asteroid, too low to be created by any of the natural phenomena of the current universe.

An international team of cosmologists led by the Department of Theoretical Physics of the Autonomous University of Madrid (UAM) and the Institute of Theoretical Physics, attached to the UAM and the Higher Council for Scientific Research (CSIC), in Spain all these entities, have proposed that primordial black holes, whose existence has been merely hypothetical, could have been produced by an increase in the temperature of the universe during their first moments of existence. And that if they really exist, they would surely be dark matter.

According to the authors of the study, that same increase in temperature would have caused the formation of gravitational waves (small deformations of space-time that propagate in a similar way to waves on the surface of a lake) that today we could detect with a system of satellites. detectors with adequate sensitivity.

“Since primordial black holes and gravitational waves have their origin in the same physical process, the detection of the latter would constitute a valuable source of information. For example, the frequency of gravitational waves would make it possible to determine the mass of primordial black holes”, highlights the team led by Guillermo Ballesteros, from the UAM.

In this way, the work jointly offers a new hypothesis to explain the nature of dark matter.

Dark matter

One of the main open problems in cosmology is the nature of ‘dark matter’, which is the most abundant type of matter in the universe (approximately 85% of the total matter). Its existence is inferred from astrophysical and cosmological observations, such as the rotational motion of spiral galaxies.

Unlike ordinary matter (the stuff from which everything we know in our daily lives is made and from which the astronomical objects we observe to the ends of the universe are made), dark matter cannot be directly observed. The word “dark” refers to this physical property. And logically, this makes the study of its composition and origin extremely difficult.

The most popular hypothesis assumes that dark matter consists of particles that interact very weakly (particularly with electromagnetic radiation). However, the persistent lack of detections of such particles (despite enormous experimental efforts devoted to it) leads physicists to consider other possibilities as well.

primordial black holes

One possibility is primordial black holes. Like any black hole, primordial black holes are extremely dense regions of space-time, to the point that not even light can escape their gravitational pull.

The name “primordial” refers to the fact that, unlike usual black holes, its origin is not the collapse of stars in the late universe, but rather high concentrations of matter and energy from the early universe.

These areas of high density could have formed from quantum fluctuations generated in a phase of the universe known as “primordial inflation.” It is believed that during this phase the universe expanded exponentially rapidly, an idea that was proposed in the 1980s to explain, among other things, the great similarity between very distant regions of the universe.

In addition, primordial inflation is also capable of accounting for the seeds of density that gave rise to the structures present in the universe, such as galaxies. Similarly, primordial seeds of sufficient density could explain the formation of black holes.

The most massive black holes reside in the centers of galaxies, as apparently occurs in the galaxy in the photo, NGC 1300. The lowest mass black holes are those formed from the corpses of stars and have not yet had a chance to swallow much matter and substantially increase its mass. However, there may be plenty of primordial black holes out there, with masses much lower than those of black holes created from stars. Those primordial black holes could be the dark matter of the universe. (Photo: NASA/ESA)

Transient rise in temperature

Most models of cosmological inflation assume that the temperature of the universe during primordial inflation was extremely low compared to earlier times. The work carried out at the UAM studies the effects of a transient increase in temperature during this phase.

“This increase in temperature would be related to the formation of a population of black holes. As a consequence of the sudden increase in temperature during inflation, the number of primordial black holes increases considerably, being able to account for the amount of dark matter present in the universe”, the authors of the study detail.

“To account for the dark matter in the universe,” they add, “the mass of each primordial black hole would have to be about a million times less than that of Earth. Due to their high density, these black holes would have a size comparable to that of an atom, which corresponds to gravitational waves of about 0.01 Hz in frequency.

“This type of gravitational waves —they continue— is beyond the precision of currently existing experiments, but they could be observed with future detectors in the next decade. In particular, the international LISA collaboration, already underway, has the right characteristics to achieve this.”

“The detection of these types of gravitational waves could represent not only a sensational milestone in the physics of gravitation, but also a fundamental advance in solving the dark matter problem. In addition, it would mean a great progress, perhaps radical, in our way of understanding the physics of the early universe”, conclude the authors of the study.

The study is titled “Primordial black holes and gravitational waves from dissipation during inflation”. And it has been published in the Journal of Cosmology and Astroparticle Physics. (Source: UAM / NCYT by Amazings)