A machine learning algorithm discovered up to 5,000 potential gravitational lenses earlier this year, which could revolutionize our ability to trace the development of galaxies since the Big Bang.
According to astronomer Kim-Vy Tran of ASTRO 3D and UNSW Sydney, and colleagues, the Keck Observatory in Hawaii and the Very Large Telescope in Chile were used to evaluate 77 of the lenses. With the help of her international team, she was able to prove that 68 of the 77 are powerful gravitational lenses that span huge distances in space.
With an 88% success rate, the algorithm appears to be trustworthy, and thousands of new gravitational lenses may exist. Only about a hundred gravitational lenses are currently in regular use, making them difficult to come by.
In a paper by Kim-Vy Tran that was just published in the Astronomical Journal, Dr. Colin Jacobs, a data scientist at ASTRO 3D and Swinburne University, presents spectroscopic confirmation of strong gravitational lenses that had previously been discovered.
The project is a component of the AGEL (ASTRO 3D Galaxy Evolution) survey.
Dr. Tran from the ARC Centre of Excellence for All Sky Astrophysics in 3-Dimensions (ASTRO3D) and the University of NSW says, “Our spectroscopy allowed us to map a 3D picture of the gravitational lenses to show they are genuine and not just a random superposition” (UNSW).
With AGEL, she says, “our objective is to spectroscopically confirm about 100 strong gravitational lenses that can be seen all year long from both the Northern and Southern hemispheres.”
The researchers from Australia, the United States, the United Kingdom, and Chile worked together to produce the paper.
The creation of the algorithm to search for specific digital signatures enabled the work.
Dr. Tran says, “With that, we could tell the difference between many thousands of lenses and just a few handfuls.”
Einstein thought that light would bend around massive objects in space in a way similar to how light bends when it passes through a lens. This led to the discovery of gravitational lensing, which is when light bends around a massive object in space.
It enlarges images of galaxies that we would not normally be able to see, significantly enhancing their brightness.
Astronomers have been using this method to look at faraway galaxies for a long time, but it has been hard to find these cosmic magnifying glasses in the first place.
Dr. Tran says that because these lenses are so small, it will be hard to tell if an image is blurry.
These lenses should enable us to “see” the invisible dark matter that makes up the majority of the universe, in addition to enabling us to see objects that are millions of light years away with greater clarity.
According to Dr. Tran, the majority of the mass is dark. We can determine how much light is bent by measuring how much mass is present since we know that mass bends light.
We will also be able to see a more complete picture of the timeline almost back to the Big Bang if there are many more gravitational lenses at different distances.
You have a better chance of surveying these farther-off objects if you have more magnifying glasses. The demographics of very young galaxies can hopefully be better measured, says Dr. Tran.
Then there is a great deal of evolution taking place between those very early first galaxies and us, with tiny star-forming regions transforming pristine gas into the first stars of the sun, the Milky Way.
So, using these lenses at different distances, we can look at different points in the history of the universe to see how things have changed from the first galaxies to the present day.
The members of Dr. Tran’s international team each brought a unique area of expertise to the table.
In order to start the project in the first place and continue with all of the follow-up observations, she says, “Being able to collaborate with people at different universities has been so crucial.”
According to Professor Stuart Wyithe of the University of Melbourne and Director of the ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (Astro 3D), each gravitational lens is different and provides us with new information.
In addition to being stunning objects, gravitational lenses offer a window into understanding how mass is distributed in extremely distant galaxies, which cannot be seen using other methods. “The team opens up the opportunity to see how galaxies get their mass by introducing ways to use these new large data sets of the sky to search for many new gravitational lenses,” he says.
Dr. Tran’s co-science lead on the paper, Professor Karl Glazebrook of Swinburne University, paid respect to the earlier work.
The inventor of this algorithm is Dr. Colin Jacobs of Swinburne University. He narrowed the sample down to 5,000 by sorting through tens of millions of galaxy images. “We never anticipated the success rate to be so high,” the man claims.
With the Hubble Space Telescope, we are now able to see images of these lenses, and they range from being jaw-droppingly beautiful to being incredibly strange and challenging to understand.
Another co-science lead on the paper, Associate Professor Tucker Jones of UC Davis, called the new sample “a giant step forward in learning how galaxies form over the history of the Universe.”
These early galaxies typically resemble small fuzzy blobs, but lensing magnification has allowed us to see their structure in much greater detail. According to him, they are the perfect objects for our most potent telescopes to observe, providing us with the clearest view of the early universe.
As a result of the lensing effect, we are able to learn about the appearance, composition, and interactions of these young galaxies.
Researchers from the University of New South Wales, Swinburne University of Technology, Australian National University, Curtin University, University of Queensland, University of California, Davis, University of Portsmouth, University of the United Kingdom, and University of Chile collaborated on the study.
The Australian Research Council (ARC) and six partner Australian universities—The Australian National University, The University of Sydney, The University of Melbourne, Swinburne University of Technology, The University of Western Australia, and Curtin University—have jointly funded the $40 million ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D).
