Astronomers from the University of Melbourne are challenging the current
thinking about the nature of the universe’s dark matter by checking out
its effect on light.

Most of the mass of the universe is thought to exist as ‘dark matter’ –
something that can’t be seen but is known to exist. Traditionally, it
was thought that dark matter became extremely concentrated in the centre
of galaxies.

“In a spiral galaxy in the Pegasus constellation, we found this not to
be the case,” says PhD student, Cathryn Trott. “Dark matter plays an
insignificant role in the central regions of this galaxy.”

Ms Trott studied the way mass was distributed in the galaxy, focusing in
particular on its unseen dark matter halo.
She was able to do this because the spiral galaxy (2237+0305) studied
lies directly in front of a very bright distant quasar. The light from
the quasar is deflected by the mass of the galaxy, allowing astronomers
to study how mass is distributed in the unseen dark matter of the

These research results challenge standard thinking about the nature of
dark matter.

“It suggests we need to rethink the way dark matter affects the
structure of the universe,” Ms Trott says. “This has far reaching
implications for modern cosmology.”

Ms Trott is continuing her research at telescopes in NSW and India to
further identify the shape of the dark matter halo and to measure the
mass of dark matter particles. She hopes this will give astronomers a
real insight into the nature of dark matter.

Ms Trott is one of sixteen young scientists presenting their discoveries
to the media, public and students for the first time, at Fresh Science.
“We’ve selected them from 105 national nominations, brought them to
Melbourne, trained them and thrown them to the [media] lions,” said
Niall Byrne, Chairman of Fresh Science. “It’s all about focussing public
and media attention on Australian scientific achievement.”

Photographs of Cathryn with her dark matter galaxy on screen are

For interview: Cathryn Trott, phone: +61 3 8344 5451, mobile: +61 412
962 232

For media assistance: Jenni Metcalfe, phone +61 408 551 866

Niall Byrne
Science Communication Consultant
Byrne Young Communication Pty Ltd
PO Box 199 Drysdale 3222 Australia
Ph +61 3 5253 1391, fax +61 3 9923 6008, mobile 0417 131 977