“There’s something we just don’t understand about the internal structure of how the universe works,” said Enectali Figueroa-Feliciano, an associate professor of physics at Northwestern and the MIT Kavli Institute for Astrophysics and Space Research, reacting to what astronomers think may be the first real signal from the “dark universe.”
While studying data collected by the European Space Agency’s XMM-Newton spacecraft in September 2018, a team of researchers observed an odd spike in X-ray emission at a unique wavelength that corresponds to no known particle or atom.
Emitted from the Core of the Perseus Galaxy Cluster
The signal, the researchers thought, may have been produced by dark matter within the core of the Perseus Galaxy Cluster–one of the most massive objects in the Universe. The astronomers also detected the same unique X-ray emission from a variety of nearby galaxies, including our next-door neighbor the Andromeda Galaxy — a swirling metropolis of a trillion stars, black holes and globular clusters (pictured above). The Andromeda “nebula,” shown at the top of the page was photographed at the Yerkes Observatory around 1900. To modern eyes, this object is clearly a galaxy. At the time, though, it was described as “a mass of glowing gas,” its true identity unknown.
It wasn’t until the 1920s that Edwin Hubble, for whom the Hubble Space Telescope is named, discovered that countless galaxies existed beyond our own Milky Way galaxy, revolutionizing our understanding of the universe and our place within it. Before Hubble’s epic discovery, Most astronomers thought that all of the universe were contained within the Milky Way galaxy. Our galaxy, it was thought, was the universe.
1923, reports NASA, Hubble trained the Hooker telescope on a fuzzy patch of sky called the Great Andromeda Nebula. He found that it contained stars just like the ones in our galaxy, only dimmer. From one star, a Cepheid variable, Hubble conjectured that the Andromeda Nebula was not a nearby star cluster but rather an entire other galaxy.
Corresponds Exactly to Dark Matter Predictions
“The signal’s distribution within the galaxy corresponds exactly to what we were expecting with dark matter — that is, concentrated and intense in the center of objects and weaker and diffuse on the edges,” study co-author Oleg Ruchayskiy, of the École Polytechnique Fédérale de Lausanne (EPFL) said.
The image below shows X-ray emission from the core of the Perseus cluster (in red), as observed by the Chandra X-ray Observatory; the radio emission from the central supermassive black hole is shown in blue.
Something Out there We Can’t Sense
“This idea that there’s something out there that we can’t sense yet is one of those things that sends chills down my spine,” said Harry Nelson, professor of physics at the University of California, Santa Barbara.
“Nature is Being Coy”
“Nature is being coy,” said Figueroa-Feliciano, who works on one of the three experiments searching for dark matter that continue to this day. “”When theorists write down all the ways dark matter might interact with our particles, they find, for the simplest models, that we should have seen it already. So even though we haven’t found it yet, there’s a message there, one that we’re trying to decode now.”
“We’re all looking and somewhere, maybe even now, there’s a little bit of data that will cause someone to have an ‘Ah ha!’ moment,” said Nelson, science lead for the LUX upgrade, called LUX-ZEPLIN. Scientists have long known that dark matter is out there, silently orchestrating the universe’s movement and structure, but it remains a mystery, with experiment after experiment coming up empty handed.
Your free twice-weekly fix of stories of space and science –a random journey from Planet Earth through the Cosmos– that has the capacity to provide clues to our existence and add a much needed cosmic perspective in our Anthropocene epoch.