“The interesting thing is: we have no idea!” says Pieter van Dokkum, Sol Goldman Professor of Astronomy at Yale University, who wrote in an email to The Daily Galaxy about why ultra-diffuse galaxy DF2 contains no dark matter. “The existence of this galaxy shows that there is another pathway to creating galaxies than our standard picture, but what that might be is anyone’s guess.”
Dark matter is aptly named. It emits no light and interacts with visible matter only via gravity. But dark matter might be only the tip of an invisible universe of unknown forces. This possibility has led to a hunt for “dark photons.” Such photons are analogous to ordinary photons, but they are exchanged among particles of dark matter, and according to some models, they may have mass.
This weekend’s stories include Should We Really Be Messing with Asteroid Orbits? to Our Search for Habitable Planets Just Got a Lot Narrower to Did the Brightest-Ever Space Explosion Reveal Hints of Dark Matter? and much more.
“It is undeniable that we are profoundly puzzled, especially when it comes to the first fraction of a second that followed the Big Bang,” wrote theoretical physicist Dan Hooper, author of The Edge of Time in an email to The Daily Galaxy–Great Discoveries Channel. “I have no doubt that these earliest moments hold incredible secrets, but our universe holds its secrets closely. It is up to us to coax those secrets from its grip, transforming them from mystery into discovery.”
Astronomers studying the motions of galaxies and the character of the cosmic microwave background radiation came to realize in the last century that most of the matter in the universe was not visible. About 84 percent of the matter in the cosmos is dark matter, much of it located in halos around galaxies. It was dubbed dark matter because it does not emit light, but it is also mysterious: it is not composed of atoms or their usual constituents like electrons and protons.
“If we combine the map of the dark matter in the Milky Way with the most recent Big Bang model to explain the universe and we hypothesize the existence of space-time tunnels, what we get is that our galaxy could really contain one of these tunnels, and that the tunnel could even be the size of the galaxy itself. But there’s more,” explained Paolo Salucci, astrophysicist with SISSA and a dark matter expert. “We could even travel through this tunnel, since, based on our calculations, it could be navigable.” Salucci is among the authors of the paper published in Annals of Physics.