Possible evidence of the existence of dark matter in the traces of the first stars of the universe

Pattern of radio waves (Image courtesy Prof. Rennan Barkana)
Pattern of radio waves (Image courtesy Prof. Rennan Barkana)

An article published in the journal “Nature” describes a research into the possible evidence of the existence of dark matter. Professor Rennan Barkana of the University of Tel Aviv used data collected by the team of Professor Judd Bowman, who found what could be traces of the first stars born in the universe. Those detections also show what were interpreted as evidence of an interaction between dark matter and baryonic matter, the one also called ordinary matter.

The problem of dark matter is one of the most studied since its existence was proposed to explain certain gravitational effects observed in the universe. A number of hypotheses have been proposed to create dark matter models but the lack of experimental evidence doesn’t even allow to be certain that it really exists, so much that there are also alternative hypotheses.

The approach of Professor Rennan Barkana, Head of the Department of Astrophysics at Tel Aviv University’s School of Physics and Astronomy, to study dark matter is to go back in time. The observation of objects billions of light years away makes it possible to see them as they were billions of years ago.

Professor Judd Bowman’s team detected radio signals emitted 180 million years after the Big Bang, interpreted as traces of the first stars born in the universe. In those traces, the researchers also found that primordial hydrogen was colder than expected and according to Professor Rennan Barkana this suggests that the gas cooled gaving off heat during an interaction with dark matter.

The image shows a pattern of radio waves on the sky caused by the combination of radiation from the first stars and the effect of dark matter. Blue regions are those where the dark matter cooled down the ordinary matter most strongly.

The characteristics of that interaction suggest that dark matter is made of particles of relatively low mass: several times the proton’s but much lighter than that expected in various theoretical models. This is an indication that could change the study of dark matter.

This could be the first evidence of the existence of dark matter not deduced from gravitational effects. For this and all the other reasons connected to this research, it’s essential that it gets confirmed independently, even better if with other instruments.

According to Professor Rennan Barkana, dark matter produced a very specific pattern of radio waves that can be detected by a large array of radio antennas. Currently the ALMA radio telescope is the largest in the world but the SKA radio telescope is under construction and it could contribute also with this type of research to the progress of our knowledge of the universe.

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