Analysis of the distribution of dark matter in nearby dwarf galaxies has provided astronomers with the first observational evidence that it can “warm up” and migrate under the influence of intense star formation. The findings of scientists presented in the journal Monthly Notices of the Royal Astronomical Society.
We found a truly remarkable connection between the amount of dark matter in the centers of these tiny structures and the history of star formation in them. Our results show that dark matter is a cold, collisionless and fluid substance that can be kinematically “heated” and moved.
-Justin Reed, lead author of a study from the University of Surrey (United Kingdom)
Dwarf galaxies are small, weak structures that typically revolve around their large counterparts, like our Milky Way. Scientists believe that they contain clues to better understand the nature of dark matter (an invisible substance that makes up most of the mass of the Universe), since its content in them is considered to be significantly higher than the amount of ordinary substance. And, according to a new study, stars can be one of the keys to studying it.
During the formation of stars, a strong wind pushes gas and dust from the heart of the galaxy. As a result, its center loses its mass, which affects the amount of gravity felt by the dark matter remaining in it. With less gravitational attraction, the mysterious substance accumulates energy and leaves the center. This effect is known as heating up dark matter.
-Justin Reed
Proof of heat and motion of dark matter came from an analysis of its distribution in 16 dwarf galaxies with very different star formation histories. Scientists have discovered that those that have long ceased to form luminaries, have a higher density of dark matter in the centers compared with those that still form stars.
The data obtained set a new limit on the dark matter model: it must be able to form dwarf galaxies, which show a strong density variation at their centers, and this density must correspond to the star formation intensity.
-Justin Reed
In the future, the team plans to measure the density of dark matter in more dwarf galaxies, including dimmer ones, in order to test their findings and set new limits on the model of the mysterious substance.
Evidence of dark matter heating and movement
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