A galaxy which is 250 million light-years from Earth has no dark matter. If scientists prove that this galaxy actually does not have any dark matter, then the fundamental theory of how galaxies are formed will be denied. This will also give a scope to cold dark matter to come into light.
A doctoral candidate in astronomy at the University of Groningen in the Netherlands, Pavel Mancera Piña think that galaxies like this should not exist. Scientists have always thought that dark matter is the glue that holds a galaxy’s stars, gas and dust together. Scientists are still unable to define this existence with any theories till now.
The scientists have named this new galaxy as AGC 114905. This new galaxy is an ultra-diffuse galaxy. Ultra-diffuse galaxies are usually faint. AGC 114905 is nearly this size of our milky way but it has fewer stars.
The scientists found AGC 114905 in 2019. They suspected the galaxy must not have any dark matter as it was moving too fast. The speed of a galaxy reveals how much stuff in contains inside it. If a galaxy is too massive, the faster it will spin. Researchers can also trace how much invisible stuff a galaxy contains from its spinning.
As this new galaxy is too faint, astronomers do not have much data in the beginning as the galaxy was too faint. They observed the galaxy for 40 hours with Very Large Array from New Mexico.
By this observation, the astronomers find out how fast the gas was moving. Then they were bale to figure out the rotation speed of the galaxy and how much dark matter it contains. But the researchers ultimately find no dark matter.
Previously astronomers have found some UDGs that had too much of dark matter and some had too little. But those galaxies that had too little dark matter, researchers assumed that they have lost their dark matter through interactions with their nearby galaxies. The gravity of those dark matters has whisked the galaxy’s dark matter away. But AGC 114905 does not have any massive galaxies near it.
As astronomers thought dark matter is important for galaxy formation, and gravity keeps the materials inside a galaxy together. But as AGC 114905 does not have any dark matter then dark matter must not be essential for galaxy formation.
AGC 114905 will also give astronomers a new way to study dark matters. Researchers used to think cold dark matters are important for galaxy formation. But that did not work out in the case of AGC 114905.
The researchers also applied models of an alternative theory named Modified Newtonian dynamics to understand dark matter.
The researchers are planning to study AGC 114905 further.
The researcher paper has been published in Live Science.