From ARC Centres of Excellence for All Sky Astrophysics in 3D(AU)
Prof Julia Bryant from the University of Sydney inside the SAMI instrument at the top end of the Anglo Australian Telescope. Credit: Scott Croom/University of Sydney.
Completion of Australian-led astronomy project sheds light on the evolution of the Universe.
The complex mechanics determining how galaxies spin, grow, cluster and die have been revealed following the release of all the data gathered during a massive seven-year Australian-led astronomy research project.
The scientists observed 13 galaxies at a time, building to a total of 3068, using a custom-built instrument called the Sydney-AAO Multi-Object Integral-Field Spectrograph (SAMI), connected to the 4-metre Anglo-Australian Telescope (AAT) at Siding Spring Observatory in New South Wales.
The telescope is operated by the Australian National University.
Overseen by the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), the project used bundles of optical fibres to capture and analyse bands of colours, or spectra, at multiple points in each galaxy.
The results allowed astronomers from around the world to explore how these galaxies interacted with each other, and how they grew, sped up or slowed down over time.
No two galaxies are alike. They have different bulges, haloes, disks and rings. Some are forming new generations of stars, while others haven’t done so for billions of years. And there are powerful feedback loops in them fuelled by supermassive black holes.
“The SAMI survey lets us see the actual internal structures of galaxies, and the results have been surprising,” said lead author Professor Scott Croom from ASTRO 3D and the University of Sydney.
“The sheer size of the SAMI Survey lets us identify similarities as well as differences, so we can move closer to understanding the forces that affect the fortunes of galaxies over their very long lives.”
The survey, which began in 2013, has already formed the basis of dozens of astronomy papers, with several more in preparation. A paper describing the final data release – including, for the first time, details of 888 galaxies within galaxy clusters – was published today in MNRAS.
“The nature of galaxies depends both on how massive they are and their environment,” said Professor Croom.
“For example, they can be lonely in voids, or crowded into the dense heart of galactic clusters, or anywhere in between. The SAMI Survey shows how the internal structure of galaxies is related to their mass and environment at the same time, so we can understand how these things influence each other.”
Research arising from the survey has already revealed several unexpected outcomes.
One group of astronomers showed that the direction of a galaxy’s spin depends on the other galaxies around it, and changes depending on the galaxy’s size. Another group showed that the amount of rotation a galaxy has is primarily determined by its mass, with little influence from the surrounding environment. A third looked at galaxies that were winding down star-making, and found that for many the process began only a billion years after they drifted into the dense inner-city regions of clusters.
“The SAMI Survey was set up to help us answer some really broad top-level questions about galaxy evolution,” said co-author Dr Matt Owers from Macquarie University in Australia.
“The detailed information we’ve gathered will help us to understand fundamental questions such as: Why do galaxies look different depending on where they live in the Universe? What processes stop galaxies forming new stars and, conversely, what processes drive the formation of new stars? Why do the stars in some galaxies move in a highly ordered rotating disk, while in other galaxies their orbits are randomly oriented?”
Professor Croom added, “The survey is finished now, but by making it all public we hope that the data will continue to bear fruit from many, many years to come.”
Co-author Associate Professor Julia Bryant from ASTRO 3D and the University of Sydney said: “The next steps in this research will make use of a new Australian instrument – which we’ve called Hector – that will start operation in 2021, increasing the detail and number of galaxies that can be observed.”
When fully installed in the AAT, Hector will survey 15,000 galaxies.
The final data release paper has 41 authors, drawn from Australia, Belgium, the US, Germany, Britain, Spain and The Netherlands.
The full data set is available online through Australian Astronomical Optics (AAO) Data Central.
See the full article here .
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The ARC Centre of Excellence in All Sky Astrophysics in 3 Dimensions (AU) unifies over 200 world-leading astronomers to understand the evolution of the matter, light, and elements from the Big Bang to the present day.
We are combining Australian innovative 3D optical and radio technology with new theoretical supercomputer simulations on a massive scale, requiring new big data techniques.
Through our nationwide training and education programs, we are training young scientific leaders and inspiring high-school students into STEM sciences to prepare Australia for the next generation of telescopes: the Square Kilometre Array and the Extremely Large Optical telescopes.
The objectives for the ARC Centres of Excellence (AU) are to:
undertake highly innovative and potentially transformational research that aims to achieve international standing in the fields of research envisaged and leads to a significant advancement of capabilities and knowledge
link existing Australian research strengths and build critical mass with new capacity for interdisciplinary, collaborative approaches to address the most challenging and significant research problems
develope relationships and build new networks with major national and international centres and research programs to help strengthen research, achieve global competitiveness and gain recognition for Australian research
build Australia’s human capacity in a range of research areas by attracting and retaining, from within Australia and abroad, researchers of high international standing as well as the most promising research students
provide high-quality postgraduate and postdoctoral training environments for the next generation of researchers
offer Australian researchers opportunities to work on large-scale problems over long periods of time
establish Centres that have an impact on the wider community through interaction with higher education institutes, governments, industry and the private and non-profit sector.
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