Looking into deep space

Volume 8 Number 9 September 3 - October 8 2012

Hubble’s View of NGC 5584. Credit: NASA, ESA, A. Riess (STScI/JHU), L. Macri (Texas A&M University), and the Hubble Heritage Team (STScI/AURA)
Hubble’s View of NGC 5584. Credit: NASA, ESA, A. Riess (STScI/JHU), L. Macri (Texas A&M University), and the Hubble Heritage Team (STScI/AURA)

Melbourne academics are punching above their weight in efforts to understand the mysteries of the Universe. By Rebecca Scott.

In recent months there have been many reasons for people to gaze up into the heavens and wonder about the Universe around us.

We have watched with protective glasses the rare transit of Venus across the Sun, and witnessed the historic landing of a NASA rover on Mars. We have heard about the discovery of a particle that is almost certainly the long-sought Higgs boson, and the death of iconic astronaut Neil Armstrong has reminded us of his mission’s 1969 moon landing, ‘one small step for man, one giant leap for mankind’. All these momentous events direct our eyes and minds to the outer limits of space

Delving into and unravelling the mysteries of the Universe are major focuses for astrophysicists at the University of Melbourne. Investigating the very first moments after the Big Bang and the beginning of the Universe, detecting the first stars and galaxies, seeing through the cosmic hall of mirrors wrought by gravity, exploring black holes, radio waves, ripples in spacetime and more, are all areas of research endeavour.

Melbourne academics are involved in global and national research collaborations, such as building the world’s largest and most sensitive radio telescope, the Square Kilometre Array, in South Africa and Western Australia. They are collaborators in Geneva’s CERN laboratories, home to the Large Hadron Collider which is attempting to simulate the definitive moments after the Big Bang, and the Laser Interferometer Gravitational Wave Observatory in the USA, which is unravelling Einstein’s theories of ripples in spacetime. Our researchers work with their colleagues to answer some of science’s biggest questions. How did the universe begin? How was matter formed? How fast is the universe expanding? 

“We’re definitely punching above our weight in contributing to global scientific efforts to explore and understand the Universe,” says Professor Rachel Webster, Head of the Astrophysics Group at the University. Professor Webster leads a team analysing data from the low frequency radio telescope, the Murchison Widefield Array (MWA), a precursor to the Square Kilometre Array (SKA).

“Playing an instrumental role in the establishment of this international project shows our passion and expertise in the field of astrophysics,” she says.

For more than 20 years Melbourne physicists have been involved in the development of the Large Hadron Collider at CERN in Switzerland, the home of the recently announced discovery of the elusive Higgs boson, which could explain the origins of mass.

Teams of scientists in the Experimental and Theoretical Particle Physics Groups in the School of Physics have contributed to the software and hardware that underpinned the ATLAS experiment, one of the major experiments at the Large Hadron Collider.

They have contributed to the LHC through the development of theories that go beyond the standard model of particle physics. These will help solve deficiencies in the standard theory itself, and possibly explain mysteries such as the nature of dark matter. 

Professor Geoffrey Taylor leads the national body, the Australian Research Council Centre for Excellence for Particle Physics at the Terascale.

“This Centre’s staff reflects the high calibre of expertise in this field in Australia,” he says.

“We are proud of the contribution we have made with our colleagues and collaborators to the biggest science experiment in the world at the Large Hadron Collider.

“With the recent Higgs discovery, these are exciting times for astrophysicists. We expect more fundamental discoveries, which we hope will help unravel the mysteries of the Universe and how it began,” he says.

Dr Andrew Melatos and his team from the Astrophysics Group are deeply involved in unravelling the physics of neutron stars and black holes, and their connection to gravitational waves, known as ripples in spacetime. 

“It is expected that neutron stars and black holes will be detected in the next few years as sources of gravitational waves,” he says.

This work will form the basis of the Laser Interferometer Gravitational Wave Observatory’s attempts to prove Einstein’s theory of relativity, which predicted the existence of gravitational waves in 1916.

“It is amazing to think that when you look at the light from a star from our nearest galaxy outside our home in the Milky Way galaxy, that light started on a journey two and half million years ago to reach us today,” says Head of the School of Physics at the University of Melbourne, Professor David Jamieson.

“This is an example of the size and depth of the Universe and it takes the brightest minds to fathom and unravel its secrets,” he says.

“The global endeavour to understand the Universe on both the smallest and largest scales is a brilliant example of what our civilisation can achieve when people work together. 

“Never before in history have teams of people been so well connected and had access to such rich resources to produce so many advances in our understanding of the Universe we inhabit. This endeavour has tremendous promise to deliver more breakthroughs in the future,” he says.

Investigating the origins of the earliest galaxies is the focus of a broad range of research projects for Professor Stuart Wyithe, ARC Australian Laureate Fellow in the University’s School of Physics.

He says that scientists know from observations that when the Universe was around 300,000 years old it was full of neutral hydrogen atomic gas and there were no stars or galaxies.

The common theory is that after a fireball created the Big Bang, the Universe started expanding at a very rapid rate.

During this expansion stars formed and ionised hydrogen, which then broke apart electrons and protons into separate entities. This process heated the Universe to 10,000 degrees, affecting the formation and evolution of subsequent stars and galaxies.

“We have however, never been able to observe the birth of the first galaxies which are still beyond the reach of the Hubble and other telescopes,” he says.

“In a major project we are interested in finding the earliest galaxies through the detection of radio signals from the formation of the first stars in the Universe,” he says.

“Using the MWA telescope which can observe low frequency radio waves at length – will provide us with that reach.”

Although scientists won’t be able to observe the galaxies they will be able to measure the hydrogen gas that surrounds the galaxies.

“By measuring the hydrogen we will be able to determine when the first galaxies appeared, how big they were and what sort of stars and planets they have in them,” he says.

Professor Wyithe has also investigated the impact of gravitational lensing on our quest to know the early Universe. 

Gravitational lensing, or the bending of light from very distant galaxies, causes their images to be magnified and distorted, so there appear to be more than are actually there.

Professor Wyithe led a study which found this gravitational cosmic ‘hall of mirrors’ is distorting the number and shape of the most distant galaxies by magnifying the closer foreground galaxies.

A more recent project involves a team working on a large super-computer simulation program to interpret the findings from telescopes like the MWA and, eventually the SKA. 

The Dark-ages, Reionisation and Galaxy-Formation Simulation (DRAGONS) project will simulate the formation of the first galaxies and their effect on hydrogen in the Universe using an integrated suite of state-of-the-art models. 

“This project will help to answer the fundamental questions such as how and when the first galaxies formed, what they looked like, and how massive they were,” Professor Wyithe says.

Professor Rachel Webster said the research from the low frequency radio waves will not just help inform us about the Universe but will have other applications.

“We are learning how to transport large amounts of data and analyse them for key information. This will have definite application in other fields such as medicine,” she says.

Due to these researchers and their collaborative efforts in the global endeavour to understand our Universe, in coming years people will gaze up at the stars and know and ponder possibilities, so much more than we have ever before.

www.astro.physics.unimelb.edu.au

Visions explores the science behind the recent probable discovery of the Higgs boson at
www.visions.unimelb.edu.au