Astronomers have found the world’s biggest ‘ghost galaxy,’ which is made up of 99.99 percent dark matter.
The finding puts the galaxy, dubbed Dragonfly44, to the status of the darkest known galaxy in the whole cosmos.
Dragonfly44 was discovered in 2014 by astronomers near Hawaii, but only recent studies have verified its massive size and offered information on how it maintains stability. Scientists were perplexed as to how the black galaxy could have a comparable mass to the Milky Way but only contain 1% of the stars.
They contended that if this were the case, it would have torn itself apart using just its own gravitational pull. The explanation seems to be in dark matter.
Astronomers believe that the ghost galaxy, which is so weakly lighted that it went undetected for decades, would have to be 99.9 percent dark energy to maintain its size. It would have imploded in on itself long ago if the only thing keeping it together was its own gravitational pull.
Yale University astronomer Marla Geha said: “I’m hoping these objects are rather rare and/or only form in special environments such as a dense galaxy cluster. Otherwise, we may need to rewrite galaxy formation.”
According to NASA, dark matter accounts for just 27 percent of the visible universe, and no one knows what it is or how it functions – we only know it exists because it impacts the expansion of the universe.
Lead researcher Pieter van Dokkum said: “They are found in a dense, violent region of space filled with dark matter and galaxies whizzing around, so we think they must be cloaked in their own invisible dark matter ‘shields’ that are protecting them from this intergalactic assault.”
[This is an updated version of the previous article]
Reference(s): Research Paper