Solve the puzzle soon? – Maybe a whole chain of galaxies without dark matter

Two mysterious galaxies without dark matter are likely part of a true chain of up to eleven similar objects, all of which lack the mysterious matter that has only been described theoretically so far. This was discovered by a research team led by astronomer Peter van Dokkum of Yale University.

Dokkum has already discovered the galaxies DF2 and DF4 and is now believed to be close to solving the mystery. Galaxies without dark matter are the result of a massive collision about eight billion years ago. His team may have found the two galaxies that originally collided with dark matter. Thus, the research team presents a series of measurable predictions that can now be verified.

Since their discovery in 2018 and 2020, galaxies NGC 1052-DF2 and NGC 1052-DF4 have provided astronomers with a “complete puzzle”. The motions of stars in the two galaxies can be explained almost exclusively by their own gravity, and unlike all other known galaxies, the measured data leave no room for dark matter. Simulations suggested that highly unusual collisions could create galaxies without dark matter, and van Dokkum’s research team now sees this as an explanation. They believe that two ancestral galaxies collided billions of years ago. Their stars would have sailed past each other and remained in galaxies like dark matter.

However, interstellar gas from both galaxies from the regions between their stars may collide, condense and become slower as a result. New galaxies then formed among the volatile predecessor galaxies, without any dark matter at all. With this hypothesis, they would have searched the sky for the remnants of this collision and allegedly actually found what they were looking for. In total, they found seven to eleven potential galaxies lined up like a chain, with DF2 and DF4 at the end. Therefore, they all share characteristics of the two galaxies without dark matter. The team even found the remains of the two predecessor galaxies.

supposed process

(Photo: P. van Dokkum et al / Nature 2022)

It can now be confirmed whether this theory is correct experimentally: on the one hand, it can be checked whether the specified galaxies are in fact all in one line and whether their speed is proportional to the attempt to explain. In addition, the question arises whether they are all devoid of dark matter. The putative ancestral galaxies, in turn, should contain a relatively large amount of dark matter. This can be verified using the star movements there.

However, not everyone was convinced by this theory, as the American Science Journal wrote temper natureVan Dokkum and his team published the research. The precisely assumed process must also be reproducible using simulations, says astronomer Mireia Montes.

The mysterious dark matter has not yet been directly observed, but its effect can be seen everywhere in space. Admittedly, it does exist. What exactly this is about is one of the most pressing questions in modern physics. The DF2 and DF4 galaxies and the alleged lack of dark matter there have been the subject of controversy for years. Meanwhile, other measurements have suggested that the measurement they first detected is much closer to us than had been assumed. The puzzle seems to have been solved. However, it was later decided that it was too far away. So there was still more dark matter missing. It is not yet possible to predict whether the solution to the puzzle approximates the supposed collision. If so, it may also help greatly in the study of dark matter.


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