The completion of the Australia-led astronomy project sheds light on the evolution of the Universe.
The complex mechanics that determine how galaxies spin, grow, cluster and die have been revealed after the release of all the data collected during a massive seven-year Australian-led astronomical research project.
The scientists observed 13 galaxies simultaneously, for a total of 3,068, using a custom-built instrument called the Sydney-AAO Multi-Object Integral-Field Spectrograph (SAMI) connected to the 4-meter Anglo-Australian Telescope (AAT) at Siding Spring Observatory in New South Wales. The telescope is operated by the Australian National University.
Supervised by the ARC Center of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), the project used bundles of optical fibers to capture and analyze bands of colors or spectra at multiple points in each galaxy.
The results allowed astronomers from around the world to study how these galaxies interacted, and how they grew, accelerated, or slowed over time.
The SAMI instrument in the Anglo Australian Telescope is being readied for action. Credit: Ángel R. López-Sánchez (AAO-MQ)
No two galaxies are the same. They have different bulges, halos, disks and rings. Some form new generations of stars, while others have not done so for billions of years. And it has powerful feedback loops fed by supermassive black holes.
“The SAMI survey shows us the actual internal structures of galaxies, and the results were surprising,” said lead author Professor Scott Croom of ASTRO 3D and the University of Sydney.
“The sheer size of the SAMI survey allows us to identify similarities as well as differences so that we can better understand the forces that influence the fate of galaxies over their very long lifetimes.”
The study, which started in 2013, has already formed the basis of dozens of astronomy papers, and more are in preparation. A paper was published today (Feb. 2, 2021) in the journal describing the final data release – including, for the first time, details of 888 galaxies in galaxy clusters. Monthly Communications from the Royal Astronomical Society.
“The nature of galaxies depends on how massive they are and their environment,” said Professor Croom.
For example, they can be lonely in voids, or densely packed in the dense heart of galactic clusters, or somewhere in between. The SAMI survey shows how the internal structure of galaxies is simultaneously related to their mass and environment, so we can understand how these things influence each other. “
Research following the study has already yielded several unexpected outcomes.
A group of astronomers showed that the direction of a galaxy’s rotation depends on the other galaxies around it, and changes depending on the size of the galaxy. Another group showed that the degree of rotation of a galaxy is mainly determined by its mass, with little influence from the environment. A third looked at galaxies that were making stars and found that for many, the process began only a billion years after they drifted into the dense inner-city areas of clusters.
A / Prof. Julia Bryant of the University of Sydney in the SAMI instrument at the top of the Anglo Australian Telescope. Credit: Scott Croom / University of Sydney
“The SAMI survey was designed to help us answer some very broad top-level questions about galaxy evolution,” said study co-author Dr. Matt Owers of Macquarie University in Australia.
“The detailed information we have gathered will help us understand fundamental questions such as, why do galaxies look different depending on where they live in the Universe? Which processes prevent galaxies from forming new stars and, conversely, which processes control 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 research is now complete, but by making it all public, we hope the data will continue to bear fruit for many, many years to come.”
Co-author, Associate Professor Julia Bryant of ASTRO 3D and the University of Sydney said: “The next steps in this research will use a new Australian tool – which we have named Hector – which will go into effect in 2021, bringing the details increase. and the number of galaxies that can be observed. “
When fully installed in the AAT, Hector will investigate 15,000 galaxies.
Reference: “The SAMI Galaxy Survey: the third and final data release” by Scott M Croom, Matt S Owers, Nicholas Scott, Henry Poetrodjojo, Brent Groves, Jesse van de Sande, Tania M Barone, Luca Cortese, Francesco D’Eugenio, Joss Bland-Hawthorn, Julia Bryant, Sree Oh, Sarah Brough, James Agostino, Sarah Casura, Barbara Catinella, Matthew Colless, Gerald Cecil, Roger L Davies, Michael J Drinkwater, Simon P Driver, Ignacio Ferreras, Caroline Foster, Amelia Fraser- McKelvie, Jon Lawrence, Sarah K Leslie, Jochen Liske, Ángel R López-Sánchez, Nuria PF Lorente, Rebecca McElroy, Anne M Medling, Danail Obreschkow, Samuel N Richards, Rob Sharp, Sarah M Sweet, Dan S Taranu, Edward N Taylor , Edoardo Tescari, Adam D Thomas, James Tocknell and Sam P Vaughan, February 1, 2021, Monthly Communications from the Royal Astronomical Society.
DOI: 10.1093 / mnras / stab229
The final data release document has 41 authors from Australia, Belgium, USA, Germany, UK, Spain and the Netherlands.
The full dataset is available online through Australian Astronomical Optics (AAO) Data Central.