Not to be confused with dark matter, baryonic matter (the stuff that makes up the visible ‘normal’ matter in the universe) was – until recently – in short supply in our universe. Half of it was missing.
A student at Monash University has made a breakthrough in the field of astrophysics, discovering what – until now – has been referred to as the Universe’s “missing mass”. During a three month targeted X-ray search for the missing matter, Amelia Fraser-McKelvie and her team at the Monash School of Physics, found it – or at least some of it.
The Student’s Surprising Discovery
What makes this discovery more noteworthy is the fact that Ms. Fraser-McKelvie isn’t a career researcher, or even studying at a postgraduate level. She is a 22-year-old undergraduate Aerospace Engineering/Science student who discovered the missing mass during her summer scholarship, working with two astrophysicists at the School of Physics, Dr Jasmina Lazendic-Galloway and Dr Kevin Pimbblet.
Monash’s School of Physics put out a request for students who were interested in a 6-week paid astrophysics internship during a vacation period, and chose Ms Fraser-McKelvie from a large pool of applicants. Dr Pimbblet, a lecturer in the School of Physics, put the magnitude of the discovery in context by explaining that scientists had been hunting for this missing baryonic matter for decades.
The Universe’s Missing Mass
“From a theoretical viewpoint, it was thought that there should be about double the amount of matter in the local Universe compared to what we observed. It was predicted that most of this missing mass should be located in large-scale cosmic structures called filaments – a bit like thick shoelaces,” said Dr Pimbblet.
Astrophysicists also predicted that the matter would be low in density, but high in temperature – approximately one million degrees Celsius. This meant that the matter should have been observable in the X-ray spectrum. Amelia Fraser-McKelvie’s discovery proved that prediction correct.
How It Was Found
Ms Fraser-McKelvie said the ‘Eureka moment’ came when Dr Lazendic-Galloway closely examined the data they had collected. “Using her expert knowledge in the X-ray astronomy field, Jasmina re-analyzed our results to find that we had in fact detected the filaments in the results, where previously we believed we had not.”
X-ray observations provide important information about the physical properties of large-scale structures, which can help astrophysicists understand their true nature. Until now, they had been making deductions based only on numerical models, so the discovery is a huge leap forward in determining how much matter is actually contained in those filaments.
A Bright Future
Still a year away from undertaking her Honors (which she will complete under Dr Pimbblet’s supervision), Ms Fraser-McKelvie is being called one of Australia’s most exciting young students. She has now been published in one of the world’s oldest and most prestigious scientific journals, Monthly Notices of the Royal Astronomical Society.
“Being a published author is exciting for me, and it’s something I could never have done without the help of both Jasmina and Kevin. Their commitment and passion for this project ensured the great results and I am extremely thankful to them for all the help they have given me and time they have invested,” said Ms Fraser-McKelvie.
Dr Pimbblet said that he had under his tuition a very talented student who excelled in performing the breakthrough research.
“She has managed to get a refereed publication accepted by one of the highest ranking astronomy journals in the world as a result of her endeavors. I cannot underscore enough what an amazing achievement this is. We will use this research as a science driver for future telescopes that are being planned, such as the Australian Square Kilometer Array Pathfinder, which will be built in Western Australian.”