This lone galaxy seems to defy everything astronomers know about galactic formation.
Monthly Notices of the Royal Astronomical SocietyThat’s why it was so surprising when Mancera Piña and his team found a galaxy that they think could have formed without dark matter.
This is where dark matter comes in: Dark matter increases the weight of a galaxy without being visible to direct telescope observation. Knowing this, astronomers are accustomed to seeing galaxies rotating faster than expected due to dark matter’s influence. Scientists do actually know of another type of galaxy with no dark matter—one that’s formed from the tidal interaction of two galaxies, says, an astronomer at the Instituto de Astrofísica de Canarias in Spain, who has studied galaxies with little dark matter and was not involved with the study. The tidal pull of a neighboring galaxy can strip the dark matter from a galaxy, which explains how some galaxies might still form with dark matter, but end up with none.