by Simon Mansfield
Sydney, Australia (SPX) Aug 20, 2024
An international team of astronomers has overturned a longstanding belief that stars and dark matter interact in a mysterious way to create uniform density structures across different galaxies. This finding, published in 'Monthly Notices of the Royal Astronomical Society (MNRAS)', challenges a theory that had perplexed scientists for 25 years.
The research team, which includes scientists from Australia, the UK, Austria, and Germany, utilized the Very Large Telescope in Chile to observe and analyze 22 galaxies that are approximately four billion years old. The results revealed that the perceived uniformity in galaxy density may not be a real phenomenon but rather a consequence of oversimplified models used by astronomers.
"This homogeneity suggested that dark matter and stars must somehow compensate for each other in order to produce such regular mass structures," said Dr. Caro Derkenne, the study's lead author and a researcher at ASTRO 3D from Macquarie University.
Previously, astronomers had struggled to identify a mechanism by which dark matter and stars could interact in this way. The idea, if true, would have necessitated a major revision of current theories about galaxy formation and evolution. However, Derkenne and her team have demonstrated that the true issue lies in the methods and models used to study these galaxies.
The team employed the European Southern Observatory's Very Large Telescope to observe the galaxies in exceptional detail. These observations enabled the researchers to develop more sophisticated models that better represent the complexity of galaxies in the universe.
"In the past, people built simple models that had too many simplifications and assumptions," Derkenne explained. "Galaxies are complicated, and we have to model them with freedom or we're going to measure the wrong things. Our models ran on the OzStar supercomputer at Swinburne University, using the equivalent of about 8,000 hours of desktop computing time."
Dr. Derkenne is now using her skills in data analysis to tackle complex problems for the Australia Public Service. Reflecting on her work in astronomy, she noted, "Astronomy sets you up really well to understand big data. The real world is messy, and we don't always have all the data. No one is there to tell you the answers or if you're wrong or right. You need to accumulate data and analyze until you find something that works."
The research project leveraged MUSE (Multi Unit Spectroscopic Explorer) on the VLT to analyze the galaxies from the MAGPI survey (Middle Ages Galaxy Properties with Integral field spectroscopy). MUSE collects data in the form of spectral cubes, where each pixel contains a spectrum.
"The MAGPI project is a great example of how training workshops and collaborative space within ASTRO 3D have utilized Australia's strategic partnership with the European Southern Observatory," said ASTRO 3D Director Professor Emma Ryan-Weber. "The complex data from the ESO Very Large Telescope has not only solved a long-standing problem in Astronomy, but also enabled young scientists, such as Dr. Caro Derkenne, a platform on which to launch their careers to solve real-world problems."
The study's co-authors are affiliated with the International Centre for Radio Astronomy Research (ICRAR) in Western Australia, the University of Durham, the University of Vienna, the Australian National University, the University of New South Wales Sydney, the University of Sydney, Ludwig-Maximilians-Universitat, and the University of Queensland.
Research Report:The MAGPI Survey: Evidence Against the Bulge-Halo Conspiracy
Related Links
ASTRO 3D
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