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The dark side of globular star clusters

14 May 2015 Astronomy Now

Observations with ESO’s Very Large Telescope in Chile have discovered a new class of “dark” globular star clusters around the giant galaxy Centaurus A. These mysterious objects look similar to normal clusters, but contain much more mass and may either harbour unexpected amounts of dark matter, or contain massive black holes — neither of which was expected nor is understood.

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The dark matter conspiracy

3 May 2015 Astronomy Now

A new study finds that elliptical galaxies maintain a remarkably constant circular speed out to large distances from their centres, in the same way that spiral galaxies do. In these very different types of galaxies, stars and dark matter somehow conspire to redistribute themselves to produce this effect, or does modified Newtonian dynamics offer an explanation?

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First signs of self-interacting dark matter found?

16 April 2015 Astronomy Now

Observations of colliding galaxies made with ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope may, for the first time, have detected dark matter interacting with other dark matter in a way other than through the force of gravity.

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Dark matter even darker than once thought

28 March 2015 Astronomy Now

Astronomers using observations from the NASA/ESA Hubble Space Telescope and NASA’s Chandra X-ray Observatory have studied how dark matter in clusters of galaxies behaves when the clusters collide. The results show that dark matter interacts with itself even less than previously thought, and narrows down the options for what this mysterious substance might be.

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Dwarf galaxy’s gamma-rays hint at dark matter

11 March 2015 Kerry Hebden

An excess of gamma rays detected coming from a recently discovered dwarf galaxy named Reticulum 2, which is 98,000 light years from Earth, could provide researchers with clues about dark matter, which is the mysterious stuff that makes up most of the Universe.