Poles with a breakthrough discovery about black holes. “It will be included in textbooks”

– The nature of dark matter remains a great mystery. Most scientists believe that it consists of unknown elementary particles, says Dr. Przemysław Mróz from the Astronomical Observatory of the University of Warsaw, first author in the Nature and Astrophysical Journal Supplement Series. Astronomical observations indicate that ordinary matter that we can touch or see constitutes only 5 percent. the total mass and energy of the entire Universe.

The mystery of the black hole. No one can solve it

In the Milky Way, for 1 kg of matter contained in stars, there is 15 kg of “dark matter”, which is non-luminous and acts only through gravity. – The problem is that despite many decades of efforts, no experiment, including experiments conducted using the Large Hadron Collider, has led to the discovery of new particles that could create dark matter – says the scientist.

In 2015, the first direct observation of gravitational waves from a pair of merging black holes was made. Over 90 more such phenomena were discovered then. It was noted that black holes found using gravitational waves are much more massive (typically 20-100 solar masses) than those previously known in the Milky Way (typically 5-20 solar masses). The theory that explained the differences in these quantities assumes the existence of the so-called a primordial black hole that could have been created at very early stages of the evolution of the Universe.

Since the discovery of gravitational waves, there has been increasing speculation that such black holes could potentially account for much, if not all, of the dark matter in the universe. Polish scientists concluded that this hypothesis could be verified using astronomical observations. “We know that large amounts of dark matter are also found in our Milky Way. So if we assume that dark matter consists of massive black holes, we should detect them in our immediate cosmic environment,” we read in the scientists’ report on their study.

Polish scientists with a breakthrough discovery. “It will be included in textbooks”

In a recent publication in the Astrophysical Journal Supplement, OGLE astronomers presented nearly two decades of observations of approximately 80 million stars in a neighboring galaxy called the Large Magellanic Cloud. The data comes from the third and fourth phases of the OGLE project and was collected in 2001-2020. This is the longest, largest and most accurate time series of observations of this type in history.

The occurrence of microlensing phenomena was analyzed, i.e. situations when three objects: the observer, the light source and the lens object, align almost exactly in one line in space. This is the only way to make black holes that do not glow. – If all dark matter consisted of black holes with a mass of 10 solar masses, we should have detected a total of 258 microlensing events. In the case of black holes with a mass of 100 solar masses – 99 phenomena, 1000 solar masses – 27 phenomena – says Dr. Mróz.

Meanwhile, astronomers found “only” 13 microlensing events in the OGLE data. Moreover, most of them were relatively short. It lasted less than 100 days. – This indicates that massive black holes can constitute at most a small fraction of dark matter – explains the scientist. Detailed calculations have shown that black holes with a mass of 10 solar masses can constitute at most 1.2 percent. dark matter, 100 solar masses – 3.0 percent dark matter, 1000 solar masses – 11 percent dark matter.

To put it very simply, this means that primordial black holes cannot both be sources of gravitational waves and create a significant part of dark matter. Other explanations for the large masses of black holes are therefore much more likely. – The published works are a summary of over 30 years of activities of the OGLE project in the field of dark matter research, the search for which was one of the basic driving forces behind its creation. Undoubtedly, the results just presented are our “opus magnum” and will be included in astronomy textbooks for many years – sums up Prof. Andrzej Udalski, leader of the OGLE project.