Active galaxies point to new physics of cosmic expansion

Investigating the history of our cosmos with a large sample of distant 'active' galaxies observed by ESA's XMM-Newton, a team of astronomers found there might be more to the early expansion of the universe than predicted ...

Is dark matter made of primordial black holes?

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 ...

Image: Hubble finds an Einstein ring

This image is packed full of galaxies! A keen eye can spot exquisite elliptical galaxies and spectacular spirals, seen at various orientations: edge-on with the plane of the galaxy visible, face-on to show off magnificent ...

A new bound on axions

An axion is a hypothetical elementary particle whose existence was postulated in order to explain why certain subatomic reactions appear to violate basic symmetry constraints, in particular symmetry in time. The 1980 Nobel ...

Gravitational waves measure the universe

The direct detection of gravitational waves from at least five sources during the past two years offers spectacular confirmation of Einstein's model of gravity and space-time. Modeling of these events has also provided information ...

New insights on dark energy

The universe is not only expanding - it is accelerating outward, driven by what is commonly referred to as "dark energy." The term is a poetic analogy to label for dark matter, the mysterious material that dominates the matter ...

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