Tag Archives: astrophysics

Spin doctors: Astrophysicists find when galaxies rotate, size matters

Sky survey provides clues to how they change over time.

A simulation showing a section of the Universe at its broadest scale. A web of cosmic filaments forms a lattice of matter, enclosing vast voids. Credit: Tiamat simulation, Greg Poole

The direction in which a galaxy spins depends on its mass, researchers have found.

A team of astrophysicists analysed 1418 galaxies and found that small ones are likely to spin on a different axis to large ones. The rotation was measured in relation to each galaxy’s closest “cosmic filament” – the largest structures in the universe.

Filaments are massive thread-like formations, comprising huge amounts of matter – including galaxies, gas and, modelling implies, dark matter. They can be 500 million light years long but just 20 million light years wide. At their largest scale, the filaments divide the universe into a vast gravitationally linked lattice interspersed with enormous dark matter voids.

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Birth of our hot Universe

An Australian physicist is unravelling the mystery of how the hot, brilliant stars we see today emerged from our Universe’s “dark age”.

Stuart Wyithe’s models of an early universe will be explored by the next generation of telescope. Credit: Prime Minister's Science Prizes/Bearcage
Stuart Wyithe’s models of an early universe will be explored by the next generation of telescope. Credit: Prime Minister’s Science Prizes/Bearcage

Theoretical physicist Prof Stuart Wyithe is one of the world’s leading thinkers on the Universe as it was 13 billion years ago, when there were no stars or galaxies, just cold gas.

In the next few years astronomers will learn much more as powerful new telescopes come online.

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Massive galaxy survey confirms accelerating Universe

The Universe is definitely getting bigger, faster—and astronomers using the Anglo-Australian Telescope in NSW have confirmed it.

The WiggleZ survey looked at over 200,000 visible galaxies (middle), but also gave insights into dark matter (the green grid that deforms the gravity field) and dark energy (the purple grid). Credit: NASA/JPL-Caltech
The WiggleZ survey looked at over 200,000 visible galaxies (centre), but also gave insights into dark matter (the green grid that deforms the gravity field) and dark energy (the purple grid). Credit: NASA/JPL-Caltec

The results are now in for WiggleZ, a survey of the night sky, spanning 200,000 galaxies and billions of years of cosmic history.

“This puts a nail in it. Clearly the universe is accelerating, and clearly there is something like dark energy,” says Prof Matthew Colless, director of the Australian Astronomical Observatory and a member of the WiggleZ team.
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