Getting the measure of the Universe
Merging galaxy NGC 660 (Image courtesy of the NASA-Sloan Atlas)
Tremendous technological advances, like those behind the Hubble Space Telescope, give astronomers access to vast quantities of detailed information – and a concomitant need to clarify, integrate and ensure the accuracy of their findings.
Monash University astrophysicist Dr Michael Brown, whose research into the growth of galaxies over the past 10 billion years has been recognised by an Australian Research Council Future Fellowship, has devoted much of the past 18 months to checking facts.
This is no trivial matter when you are talking about galaxies five billion light years away. Dr Brown, from the School of Physics, aims for accuracy within 10 per cent, closer than anyone would have dreamed of even a decade ago.
“It’s a field that’s in rapid progress,” Dr Brown said.
"Twenty years ago we just couldn’t see galaxies that far away. Now we can see over much of the age of the Universe with our telescopes and we are trying to integrate all that knowledge. A lot of it needs to be figured out – we get first impressions, they’re wrong; we get more data, and it confronts our relatively new theories.”
Through systematic cross-checking using different measuring methods, Dr Brown is developing a robust web of reliable results.
“When we measure a galaxy, are we getting how bright it is absolutely right? Its mass? Its distance? Testing those fundamentals has been very interesting to me.”
This painstaking work underpins his research on the history of the Universe. His particular focus is on how galaxies, like the Milky Way in which we live, have grown since their formation during a turbulent era, 10 billion or so years ago, when the universe cooled after the Big Bang and stars were born.
“Our telescopes are like time machines,” he said.
“Light takes so long to travel to us from the distant parts of the Universe, that we can see the Universe as it was a long time ago rather than as it is now.”
But even with today’s highly sensitive digital detectors, many questions remain unanswered, including whether galaxies grow by nurturing and forming stars, or – rather like corporations – by merging with others.
Dr Brown hopes his study of galaxies like our own may help piece together the puzzle.
“In palaeontology, you see bones from different animals, from different times in history, and you try to connect them as an evolutionary sequence,” he said.
“We’re trying to do the same thing with galaxies.”