A new study limits the contribution of black holes, dark matter

Statistical analysis of 740 supernovae showed that black holes may be no more than 40 percent of dark matter existing in the universe, which in turn scored another nail in the coffin of the theory of massive astrophysical compact halo objects. According to this theory, the source of dark matter may be primordial black holes. Observation of two American scientists from the University of California at Berkeley have questioned this theory.

A new study limits the contribution of black holes, dark matter

In February 2016, scientists laser interferometric gravitational-wave Observatory (LIGO) announced a new era in astronomy. Researchers first discovered the gravitational waves predicted by a pair of colliding black holes. If you do not take into account the very nature of an amazing discovery, detection of gravitational waves has revived the old theory that dark matter is a derivative of massive astrophysical compact halo object (MACHO), an ultra-objects emitting light.

According to current projections for dark matter could account for up to 85 per cent of the entire universe of matter, but physicists still have not found that matter, so do not know what it is. The theme of the existence of dark matter has gathered around himself an active discussion after the American astronomer Vera Rubin in 70 years, studying the rotation curves of galaxies, revealed discrepancies between predicted circular motion of galaxies and observe the movement of (the star on the edge of galaxies should rotate slower than those that are closer the galactic center, but observation showed that the rate of rotation of the external and internal star actually was the same). This fact became known as "the problem of the rotation of the galaxy," was one of the main evidence for the existence of dark matter. However, the question of what constitutes dark matter still remained and remains open. Over the next few decades, it was proposed many candidates for dark matter. Today, the most popular are those particle as axions or weakly interacting particles. However, several decades earlier proposed objects MACHO theory (in particular black holes) were considered as the main source of dark matter. According to this theory, dark matter is actually made of baryonic particles (particles of ordinary matter, which can be seen), moving in interstellar space, not being connected with any planetary system, and almost (or all) do not radiate any energy. According to the theory, the MACHO may be neutron stars, brown dwarfs, planets orphans and primordial black holes, which appeared shortly after the Big Bang.

In the 90s the theory of the MACHO-objects out of fashion. Scientists focused search for dark matter particles in the source, but the recent discovery of LIGO again fueled interest in black holes, as a possible explanation of the invisible dark matter.

Since MACHO-objects, according to the theory, does not emit any energy, these objects for the observer to be "dark", ie invisible. On this basis, the researchers expect to find them with the help of the effect of gravitational microlensing. This phenomenon of bending of light waves observed object relative to the observer due to a very strong gravitational field is very dense and massive objects are between the observed object and the observer. This effect can significantly increase the brightness is very remote from us, and let the stars to see the objects that can not be seen by conventional conventional methods of observation. The role of the gravitational lens can perform, for example, galaxies, galaxy clusters, and the same black hole. Physics Miguel Tsumalakraregi and Uros Selyakov the University of California at Berkeley, conducted a sophisticated analysis of data of 740 supernovae - extremely bright star explosions, - to monitor the contribution of primordial black holes in creating a curvature effect and increasing the supernova light. Supernova explosions are often used by astronomers to measure distances in the universe, because these objects have incredible brightness, which is very slowly reduced, allowing it to carry out calculations. The study is published in the journal Physical Review Letters.

Scientists have speculated that the deviation in the brightness of a few tenths of a percent, indicating the microlensing effect on the black holes and explains the mass of invisible dark matter is detected at least 8 out of 740 observed supernovae. However, scientists have not found any abnormalities indicative of microlensing by a black hole.

The findings do not rule out the black holes as sources of dark matter, but it is essential to limit their contribution to the volume inside the universe. It is estimated that even if black holes are actually contributing to the phenomena that is associated with dark matter, then it is no more than 40 percent. According to the authors, in their hands already and not yet published the results of a full analysis, which covered more than 1,000 supernovae and makes further reduce this figure - up to a maximum of 23 percent.

"We're back to the usual discussions. What is dark matter? It looks like good options we ran. This is a task for future generations, "- says Professor Urog Selyakov.

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