On the hunt for primordial black holes

The theory that dark matter could be made of primordial black holes a fraction of a millimeter in size has been ruled out by a team of researchers led by the Kavli Institute for the Physics and Mathematics of the Universe ...

How we discovered a glowing galactic ghoul

It's a classic Halloween tale. A group of ghost hunters visit a grand old house that is rumored to be haunted. But after thoroughly exploring, they leave disappointed: there are no ghosts to be seen. Only later, when looking ...

Dark energy vs. modified gravity: Which one will prevail?

Einstein's theory of general relativity predicts the existence of dark energy—a mysterious form of energy that permeates space and accelerates the expansion of the Universe. But what if Einstein was wrong and there was ...

Where is the universe hiding its missing mass?

Astronomers have spent decades looking for something that sounds like it would be hard to miss: about a third of the "normal" matter in the Universe. New results from NASA's Chandra X-ray Observatory may have helped them ...

Hydrogen halo lifts the veil of our galactic home

Sometimes it takes a lot of trees to see the forest. In the case of the latest discovery made by astronomers at the University of Arizona, exactly 732,225. Except that in this case, the "forest" is a veil of diffuse hydrogen ...

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