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Scientists say that they have raised recent doubts about the presence of elusive dark matter in galaxies, thus refuting the empirical relationships in support of alternative theories. Dark matter is one of the biggest enigmas of astrophysics and cosmology and is thought to account for 90% of matter in the universe.
However, its existence has been demonstrated only indirectly and has recently been questioned. The study, published in the Astrophysical Journal, offers new perspectives to understand the nature of dark matter and its relationship to ordinary matter.
From the expansion of the universe to the motion of stars in galaxies, many phenomena can not be explained by the mere presence of baryonic matter. The force of attraction generated by matter is insufficient to explain the observable gravitational effects. This led to the theory of the existence of undetectable dark matter and the idea that galaxies are embedded in its spherical halo.
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"Three years ago, a few colleagues at Case Western Reserve University strongly questioned our understanding of the universe and the in-depth work of many researchers, questioning the existence of dark matter in galaxies, "said Chiara Di Paolo, PhD student at the International School of Advanced Studies (SISSA) in Italy.
"By analyzing the rotation curves of 153 galaxies, mainly of the" classical "spiral type, they obtained an empirical relation between the total gravitational acceleration of stars (observed) and the component that we would observe in the presence of ordinary matter in the classic Newton, theory, said Di Paolo.
"This empirical relationship, which seemed valid in all the galaxies analyzed and whatever their radius, motivated the explanation of the gravitational acceleration without necessarily calling into question the dark matter, but implying, for example, Modified gravity theories such as Modified Newtonian Dynamics (MOND), she says.
Di Paolo and his collaborators wanted to verify this relationship by analyzing the rotation curves of galaxies other than the classical spiral type: 72 low surface gloss galaxies (LSB) and 34 dwarf disk galaxies. They produced more extensive results, finding a relation which, in addition to the total gravitational acceleration and its ordinary component, also implies the galactic radius and morphology of the galaxies.
"We have studied the relationship between total acceleration and its ordinary component in 106 galaxies, obtaining results different from those previously observed," said Paolo Salucci, professor of astrophysics at SISSA and the US. one of the authors of the research.
"This not only demonstrates the inaccuracy of the empirical relationship described above, but also removes doubts about the existence of dark matter in galaxies. "In addition, the new relationship found could provide crucial information on understanding the nature of this indefinite component," Salucci said.
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