The Australian Square Kilometer Array Pathfinder (ASKAP), a sophisticated radio telescope, is located at the Murchison Radio-astronomy Observatory in the Australian state of Western Australia. Led by scientists from Canada’s Queen’s University, an international team of researchers used the telescope to observe hydrogen gas in more than 600 galaxies – and unexpectedly discovered two potential polar ring galaxies.
Polar ring galaxies are considered a rare type of galaxy in which a ring of stars and gas extends perpendicular to the main disk of the galaxy. Their formation is usually explained by the merger of two galaxies, in which a larger galaxy “swallows” a smaller one. The fact that the new galaxies were identified solely through the detection of gas leads astronomers to believe that polar ring galaxies may exist far more frequently in our universe than previously thought. The union of different galaxies might not be uncommon.
“Polar ring galaxies are among the most spectacular galaxies in the universe. Our results suggest that one to three percent of the galaxies in our vicinity could have gaseous polar rings, which would be much more than optical telescopes suggest,” explains lead author Nathan Deg from Queen’s University. The galaxies, which may not be so rare after all, could help researchers not only better understand the formation of galaxies, but also get closer to the mystery of dark matter. This makes it possible to study the shape of a galaxy’s dark matter using its polar ring.
The cold hydrogen gas of a polar ring is invisible to the human eye. But researchers can measure the radio emissions it emits using radio telescopes. As an astronomical imaging expert at the University of Manitoba, Canada, Jayanne English developed the first images of the polar ring galaxies. To do this, she combined data from the Subaru telescope in Hawaii, which provided images of the galaxy disks, with data from the ASKAP telescope to image the gaseous polar rings. English made the movement of the gas clouds clear through their different colors in the images: purple-colored gas moves towards the observer, white clouds move away from him. The image shown shows the newly discovered galaxy NGC 4632 as a potential polar ring galaxy.
In the next step, the astronomers want to confirm the two striking galaxies as polar ring galaxies through further observations with different telescopes.