New imagery technique helps understand the Universe

MINNEAPOLIS / ST. PAUL (10/22/2024) — Researchers at the University of Minnesota Twin Cities College of Science and Engineering have developed a new technique that reconstructs two dimensional (2D) radio images–visual representations created from radio waves–into three dimensional (3D) "Pseudo3D cubes" to help better understand objects in the Universe.

This first-of-its-kind technique that is useful for radio images is published in the Monthly Notices of the Royal Astronomical Society, a peer-reviewed scientific journal.

Traditionally, when radio images are captured in a 2D format, the images may not allow scientists to infer what the object looks like in 3D. Transforming these images into a 3D space can help better understand the physics of galaxies, massive black holes, jet structures, and, ultimately, how the Universe works.

The researchers looked at polarized (radio) light–light that vibrates in a specific direction. We experience polarized light when we look at the glare from sunlight off a highway — it vibrates horizontally.  We then use polarized sunglasses that allow only vertical vibrating light to pass and the glare disappears. 

The research team made use of an effect called Faraday rotation, which rotates the direction of the radio polarized waves, depending on how much material they have passed through. With this, they could estimate how far each piece of the radio picture had traveled, and thus create a 3Dmodel of these phenomena happening millions of light-years away.

“We found that the shapes of the objects were very different from the impression that we got by just looking at them in a 2D space,” said Lawrence Rudnick, a Professor Emeritus in the University of Minnesota School of Physics and Astronomy. 

With this new technique, the researchers were also able to determine the direction of material expelled from massive black holes, look at how the material interacts with cosmic winds or other space weather, and analyze the structures of magnetic fields in space.

“Our technique has dramatically altered our understanding of these exotic objects. We may need to reconsider previous models on the physics of how these things work,” Rudnick added. “There is no question in my mind that we will end up with lots of surprises in the future that some objects will not look like we thought in 2D.”

Previous imagery will need to be reanalyzed using this new technique to confirm previous thoughts or bring new insights. Rudnick hopes to see this technique applied to imagery being taken in new telescope facilities around the world. 

In addition to Rudnick, the team included Craig Anderson from the Research School of Astronomy and Astrophysics at Australian National University; William Cotton from the National Radio Astronomy Observatory; Alice Pasetto from the Institute for Radio Astronomy and Astrophysics National Autonomous at the University of Mexico; Emma Alexander from the Jodrell Bank Centre for Astrophysics at the University of Manchester; and Mehrnoosh Tahani from Kavli Institute for Particle Astrophysics and Cosmology at Stanford University. 

Data for this project came from the MeerKAT radio telescope array, a facility of the South African Radio Astronomy Observatory. 

To read the full paper titled “Pseudo-3D visualization of Faraday structure in polarized radio sources: methods, science use cases, and development priorities,” visit the arXiv website.