In the truest sense of the term, it's not a real "image" of dark matter, but it's as close as we could get to seeing the mysterious force that ties galaxies together in the universe.
According to National Geographic, dark matter makes up approximately 25 percent of the universe and is not to be confused with dark energy, which takes up 70 percent and represents the force that repels gravity. Scientists have yet to directly observe dark matter because it neither absorbs nor reflects light, and even with today's high-tech telescopes and other instruments, it's impossible to detect through traditional means. But since there is a gravitational effect that manifests within the universe's many galaxies and galaxy clusters, scientists believe that dark matter, mysterious as it is, does exist.
While dark matter only takes up about a quarter of the universe, that's a fairly large percentage compared to the percentage of visible matter. The European Organization for Nuclear Research (CERN) writes on its website that the matter that makes up all of the stars and galaxies takes up a mere five percent of the universe.Traditional instruments might not be able to spot dark matter, but a team of scientists from the University of Waterloo in Ontario has come up with what is said to be a composite image of dark matter. And it could be quite an important image, as study co-author and University of Waterloo professor of astronomy Mike Hudson related in a press statement quoted by Popular Mechanics.
"For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together. This image moves us beyond predictions to something we can see and measure."Teaming up with former University of Waterloo graduate student Seth Epps, Hudson used weak gravitational lensing to come up with the composite image. This technique tends to skew the appearance of distant galaxies once "under the influence of an unseen mass" – this could oftentimes be a planet or a black hole, but for this study, it was dark matter serving as the unseen mass.Hudson and Epps then used weak gravitational lensing when blending together images from 23,000 pairs of distant galaxies located about 4.5 billion light-years away, having collected the data from the Canada-France-Hawaii Telescope in Waimea, Hawaii. Epps noted that the technique was essential in confirming that dark matter exists, and how strands of this matter connect galaxies to each other.
"By using this technique, we're not only to able to see that these dark matter filaments in the universe exist, we're able to see the extent to which these filaments connect galaxies together."This isn't the first time that an "image of dark matter" has tried to provide tangible proof that the strange and elusive "bridge" between galaxies exists. A 2008 press release from NASA detailed how the Hubble Space Telescope captured an image showing a "huge ring of dark matter" that may possibly surround the CL0024+17 galaxy cluster in the constellation Pisces.
Meanwhile, the search for some sort of actual proof of dark matter continues, even with the Waterloo duo having cobbled together a composite image of dark matter. The Guardian wrote in December 2016 that this search, which has lasted about three decades so far, has cost researchers "millions of pounds" and has yet to yield any definitive results, suggesting that "time is running out" in this search. And while some scientists believe that it may be time to come up with a different explanation, others have argued there's still a good chance of finding proof of actual dark matter particles out there in the universe.
[Featured Image by NASA]