A team of astronomers from the International Centre of Radio Astronomy Research (ICRAR) in Australia has produced a remarkable new radio image of the Milky Way. This innovative image, created by assigning different radio frequencies to RGB colors, illuminates extensive astrophysical phenomena and provides researchers with an advanced tool for examining the lifecycle of stars.
The universe, akin to a photographer”s canvas, is illuminated by various forms of electromagnetic radiation. While gamma rays are the most energetic and can damage DNA, radio waves, which are significantly safer, permeate our environment. Much of the radio radiation we encounter on Earth stems from technological sources such as AM/FM radios, WiFi, and GPS signals. However, natural sources also contribute, including quasars, active galactic nuclei, supernova remnants, and even planets like Jupiter, which emits more radio waves than the Sun.
Radio waves are particularly beneficial for astronomers due to their long wavelengths, enabling them to penetrate dust and gas clouds that obscure other radiation types. They can be observed in any weather conditions, any time of day or night, and provide insights into various physical phenomena. This ability is especially valuable for imaging young stars and their forming planets, often hidden by dense dust in other wavelengths.
Over a period exceeding 18 months, Australian scientists utilized radio telescopes to conduct a comprehensive survey of the Milky Way, requiring more than 40,000 hours of supercomputer processing time to synthesize the data into a singular expansive image of our galaxy. The newly released findings appear in a paper titled “GaLactic and extragalactic all-sky Murchison Widefield Array survey eXtended (GLEAM-X) III: Galactic plane,” published in the Publications of the Astronomical Society of Australia. The lead author, Silvia Mantovanini, is a PhD student at Curtin University.
This new image serves as an upgrade to a prior image released in 2019, which was derived from the GaLactic and Extragalactic All-sky MWA survey (GLEAM). The previous image focused on extragalactic features, whereas the current one emphasizes the Milky Way itself, boasting double the resolution, covering twice the area of sky, and exhibiting ten times the sensitivity of its predecessor.
“This vibrant image delivers an unparalleled perspective of our Galaxy at low radio frequencies,” said Mantovanini in a press release. “It provides valuable insights into the evolution of stars, including their formation in various regions of the Galaxy, how they interact with other celestial objects, and ultimately their demise.”
The image allows astronomers to differentiate between supernova remnants (SNR), which appear as large red circles, and stellar nurseries, identified as smaller blue circles. SNR emits radio waves and are crucial for understanding stellar evolution. Mantovanini expressed particular interest in SNR, stating that this new image will facilitate both the discovery and study of these remnants. Hundreds have been identified, yet many more likely exist, often masquerading as other cosmic structures due to their similarity to shells created by stellar winds.
The researchers anticipate discovering an additional 2,000 SNR along the galactic plane. “We are confident this data release will help find more faint and old elements of the SNR population, helping to fill the current gap,” the authors noted.
The image also enables astronomers to distinguish young stars from SNR, both enveloped in gas. “You can clearly identify remnants of exploded stars, represented by large red circles, while the smaller blue regions indicate stellar nurseries where new stars are actively forming,” Mantovanini explained.
This advancement highlights the capability of the new Milky Way image to differentiate between SNR and young stars. The image features white boxes that outline HII regions, which are areas of ionized hydrogen produced by the ultraviolet radiation from young stars. These regions become optically thick at low radio frequencies, making them stand out from the surrounding background.
Associate Professor Natasha Hurley-Walker, the principal investigator of the GLEAM-X survey, emphasized the significance of the image in advancing our understanding of the Milky Way”s structure. “This low-frequency image allows us to unveil large astrophysical structures in our Galaxy that are difficult to image at higher frequencies,” she stated. “No low-frequency radio image of the entire Southern Galactic Plane has been published before, marking an exciting milestone in astronomy.”
Looking ahead, this new image may not hold the title of the most sensitive and detailed for long. A global collaboration is underway to establish the Square Kilometre Array Observatory (SKAO), a powerful radio interferometer expected to deliver the highest-resolution images in astronomy. “Only the world”s largest radio telescope, the SKA Observatory”s SKA-Low telescope, set to be completed in the next decade in Western Australia, will have the capacity to surpass this image in terms of sensitivity and resolution,” noted Hurley-Walker.
