Dozens of newly discovered gravitational lenses can reveal ancient galaxies and the nature of dark matter

يمكن أن تكشف العشرات من عدسات الجاذبية المكتشفة حديثًا عن المجرات القديمة وطبيعة المادة المظلمة

Gravitational lens images from an AGEL survey. The images are centered on the foreground galaxy and include the name of the object. Each panel includes the confirmed distance to the foreground galaxy (zdef) and the far background galaxy (zsrc). Credit: Kim-Vy H. Tran et al, Astronomical Journal (2022). DOI: 10.3847 / 1538-3881 / ac7da2

Earlier this year, a machine learning algorithm identified up to 5,000 potential gravitational lenses that could transform our ability to map the evolution of galaxies since the Big Bang.

Astronomer Kim-Vy Tran of ASTRO 3D and UNSW Sydney and colleagues evaluated 77 lenses using the Keck Observatory in Hawaii and the Very Large Telescope in Chile. She and her international team confirmed that 68 out of 77 are strong players Gravity lenses It extends over vast cosmic distances.

this is success rate Out of 88% suggest that the algorithm is reliable and that we can get thousands of new gravitational lenses. Until now, gravitational lenses have been difficult to find and only about a hundred are used routinely.

The Kim-Vy Tran paper was published today in Astronomical Journal It provides spectroscopic confirmation of previously identified strong gravitational lenses using convolutional neural networks, developed by data scientist Dr Colin Jacobs at ASTRO 3D and Swinburne University.

This work is part of the ASTRO 3D Galaxy Evolution with Lenses (AGEL) survey.

“Our spectroscopy allowed us to 3D map gravitational lenses to show that they are real and not just an overlay of chance,” says corresponding author Dr Tran from the ARC Center of Excellence for All 3D Astrophysics (ASTRO3D) and the University of New South Wales (UNSW).

“Our goal with AGEL is to spectrally confirm about 100 strong observable gravitational lenses from the northern and southern hemispheres throughout the year,” she says.

The paper is the result of a worldwide collaboration with researchers from Australia, the United States, the United Kingdom and Chile.

The work was made possible by developing the algorithm to search for certain digital signatures.

“With this, we can identify several thousand lenses compared to a few,” Dr. Tran says.

Gravitational lensing was first identified as a phenomenon by Einstein who predicted that light bends around massive objects in space in the same way that light bends through a lens.

By doing so, it greatly enlarges images of galaxies that we would not otherwise be able to see.

While it has been used by astronomers to observe distant galaxies for a long time, finding these cosmic magnifying glasses in the first place has been a shock and fail.

“These lenses are very small, so if you have blurry images, you really won’t be able to detect it,” Dr. Tran says.

While these lenses allow us to see things that are millions light years More explicitly, it should also allow us to “see” the invisible dark matter that makes up most of the universe.

“We know that most of the mass is dark,” Dr. Tran says. “We know that mass bends light, so if we can measure how much light bends, then we can infer how much mass there should be.”

Having so many gravitational lenses at different distances would also give us a more complete picture of the timeline roughly going back to the Big Bang.

“The more magnifying lenses you have, the better chance you have of trying to scan these distant objects,” says Dr. Tran. “Hopefully we can better measure the demographics of very small galaxies.”

“Then somewhere between those first early galaxies and us, there’s a lot of evolution going on, with regions of young star formation turning pristine gas into the first stars into the Sun, the Milky Way.”

“So with these lenses at different distances, we can look at different points in the cosmic timeline to basically track how things change over time, between the first galaxies and now.”

Dr. Tran’s team spanned the globe, with each group providing different expertise.

“Being able to collaborate with people, at different universities, was critical, both for setting up the project in the first place, and now for all follow-up feedback,” she says.

Each gravitational lens is unique and tells us something new, says Professor Stuart Wyeth of the University of Melbourne and director of the ARC Center of Excellence for All Astrophysics in 3D.

“Aside from being beautiful objects, gravitational lenses provide a window to study how mass is distributed in galaxies too far away to be observed by other techniques. By offering ways to use these new large data sets in the sky to search for many new gravitational lenses, the team opens up the opportunity To find out how galaxies get their mass.”

Professor Karl Glazbrook of Swinburne University, and co-leader of science for Dr Tran, praised the work that went before.

“This algorithm was created by Dr. Colin Jacobs at Swinburne,” he says. “He scanned tens of millions of images of galaxies to reduce the sample to 5,000. We never dreamed that the success rate would be so high.”

“Now we are getting images of these lenses with the Hubble Space Telescope, and they range from stunningly beautiful images to images that are so bizarre that it would take a great deal of effort from us to find them.”

Associate Professor Tucker Jones of the University of California, Davis, another scientific lead on the paper, described the new sample as “a giant step forward in learning how galaxies have formed over the course of the history of the universe.”

“These early galaxies usually look like tiny, hazy blobs, but the magnification of the lens allows us to see their structure with much better accuracy. They are ideal targets for our most powerful telescopes to give us the best possible view of the early universe,” he says. .

“Thanks to the lensing effect, we can learn what these primordial galaxies look like, what they are made of, and how they interact with their surroundings.”


Artificial intelligence has found more than 1,200 gravitational lens filters


more information:
Kim-Vy H. Tran et al, AGEL survey: spectroscopic confirmation of strong gravitational lenses in selected DES and DECaLS fields using convolutional neural networks, Astronomical Journal (2022). DOI: 10.3847 / 1538-3881 / ac7da2

Submitted by the ARC Center of Excellence for All 3D Sky Astrophysics (ASTRO 3D)

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