NGC 1277: How did a galaxy form without dark matter
Astronomers have found a massive galaxy that does not contain dark matter, a mysterious substance that makes up about 85% of the universe. This finding does not fit the long-standing cosmological models, posing a challenge to our understanding of cosmic evolution and leaving researchers puzzled. The galaxy in question, NGC 1277, is about the size of the Milky Way and lies in constellation Perseus.
Why does this story matter?
Dark matter, which was first proven to exist in 1933, is one of the most mysterious components of the universe. This in part is because we have not been able to completely understand it. The NGC 1277 is the first big galaxy found to be missing dark matter and scientists are yet to understand why it is different from its counterparts.
Firstly, what is dark matter?
Dark matter is an invisible form of matter that makes up most of the universe's mass and creates its underlying structure, according to NASA. Dark matter's gravity drives normal matter (gas and dust) to collect and build up into stars and galaxies. Since it does not emit light or energy, it cannot be studied using conventional detection methods.
Dark matter has been important in understanding cosmic evolution
Dark matter first came to light when scientists noticed massive galaxies rotating at such high speed that they would fly apart were it not for the gravitational force of some unseen matter holding them together. This led to the theory that all large galaxies contain dark matter and has long been an integral assumption in cosmic evolution.
Galaxy NGC 1277 is considered a cosmic relic
What makes NGC 1277 stand apart is that it showed virtually zero interaction with other surrounding galaxies, suggesting it has no dark matter. Such galaxies are believed to be the remnants of giant galaxies that existed in the early universe and are termed cosmic relics. Cosmic relics can reveal about the composition, temperature, and density of the universe at different times in its history.
The galaxy defies current cosmological models
For the current study, the team employed an instrument called an integral field spectrograph to investigate the motion of the galaxy and estimate its mass and mass distribution. According to the current cosmological models, NGC 1277 should comprise somewhere between 10% and 70% dark matter. However, the latest findings point out that the galaxy does not contain dark matter at all.
Researchers have a few ideas that could explain NGC 1277
The team leading the study has a couple of theories that could explain the lack of dark matter in NGC 1277. "One is that the gravitational interaction with the surrounding medium within the galaxy cluster in which this galaxy is situated has stripped out the dark matter," said Anna Ferre-Mateu, a researcher from the University of La Laguna involved in the study.
The team intends to carry out more studies
The second reason is that "the dark matter was driven out of the system when the galaxy formed by the merging of protogalactic fragments, which gave rise to the relic galaxy," added Ferre-Mateu. To be more certain, the team wants to conduct further investigations. For that, they will be using the William Herschel Telescope (WHT) on the Canary Island of La Palma in Spain.
