January 19, 2022

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Do galaxies need dark matter?  The growing gap between theory and observation

Do galaxies need dark matter? The growing gap between theory and observation

| Astronomy / Physics

An international research team led by scientists from the Netherlands is reporting this No trace of dark matter has been found in the galaxy AGC 114905. There is a popular belief now that galaxies can exist only because of dark matter, the interaction of which binds them together.

Two years ago, Pavel Mancera Peña and his team at the University of Groningen reported the identification of six galaxies with little or no dark matter. Then they heard from their colleagues that they should search better, and they would find that she should be there. Now, after 40 hours of observations using the Very Large Array (VLA), scientists have confirmed what they previously observed – the existence of galaxies without dark matter.

AGC 114905 is located 250 million light-years from Earth. It is a highly diffuse (UDG) dwarf galaxy, but the term “dwarf” refers to brightness, not size. The size of the galaxy is the same as the Milky Way, but it contains about 1,000 times fewer stars. The observations and analyzes made contradict the belief that all galaxies, and certainly dwarf UDGs, can exist only because of the dark matter that holds them together.

Between July and October 2020, scientists collected data about the movement of gas in this galaxy using the VLA for 40 hours. Based on their observations, they created a graphic showing the distance of the gas from the galaxy on the X axis and the speed of its rotation on the Y axis. This is the standard method for studying the presence of dark matter. Meanwhile, the analysis showed that the motion of the gas in AGC 114905 can be explained entirely by referring only to the visible matter.

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This is what we expected and expected and it confirms our previous observations. However, the problem remains, as current theories say that AGC 114905 must contain dark matter. Our observations indicate that it does not exist. After further research, we thus have a growing contradiction between theory and observations, stwierdza Pavel Mancera Piña.

So scientists are trying to explain what happened to dark matter. According to one of their hypotheses, large neighboring galaxies could be stripped of dark matter AGC 114905. The problem is that there are no such galaxies. In order to explain this lack of dark matter on the basis of the widely accepted cosmological Lambda-CDM model, we will have to introduce parameters with extreme values, well beyond the accepted range. Also on the basis of an alternative model – Modified Newtonian Dynamics – we cannot explain the motion of gas in this galaxy.

Scientists say there is an assumption that could change the conclusions of their research. This assumption is the angle at which they think they were watching AGC 114905. However, this angle must be quite different from our assumptions in order for there to be room for the presence of dark matter in the conclusionsStudy co-author Tom Osterloo says. Meanwhile, another UDG research team. If he didn’t find any traces of dark matter there, that would be a very strong confirmation of the observations made so far.

It is worth noting here that we already reported 3 years ago that a team from Yale University discovered The first galaxy without dark matter. The method used by the Dutch is more reliable and resistant to disturbances.

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Observations of the theory of dark matter in the galaxy AGC 114905