A new, expansive view of the Milky Way reveals our galaxy in unprecedented radio color

Astronomers at the International Center for Radio Astronomy Research (ICRAR) have created the largest color low-frequency radio image of the Milky Way ever taken. This stunning new image captures the southern hemisphere of our Milky Way galaxy, revealing it across a wide range of radio wavelengths and colors of radio light.

An article describing this work was published in Publications of the Astronomical Society of Australia.

It provides astronomers new ways to study the birth, evolution and death of stars in our galaxy.

Silvia Mantovanini, Ph.D. The Curtin University ICRAR student spent 18 months and more than 40,000 hours creating the image using supercomputers at the Posey Supercomputing Research Center to process and compile data from two extensive surveys.

The research was carried out using the Murchison Widefield Array (MWA) telescope located at Inyarrimanha Ilgari Bundara, CSIRO's Murchison Radio Astronomy Observatory on Wajarri Yamaji Country in Western Australia. These were the Galactic and Extragalactic all-sky MWA (GLEAM) and GLEAM-X (GLEAM eXtended) surveys, conducted respectively for 28 nights in 2013 and 2014 and 113 nights from 2018 to 2020.

Focusing on our galaxy, the new image has twice the resolution, ten times the sensitivity, and covers twice the area of ​​the previous GLEAM image released in 2019.

This dramatic improvement in resolution, sensitivity and sky coverage allows for a more detailed and comprehensive study of the Milky Way, providing astronomers with a wealth of new data and insights.

“This bright image provides an unprecedented perspective of our galaxy at low radio frequencies,” Mantovanini said. “This provides valuable information about the evolution of stars, including their formation in different regions of the galaxy, how they interact with other celestial objects and, ultimately, their demise.”

Mantovanini's research focuses on supernova remnants—the expanding clouds of gas and energy left behind when a star explodes at the end of its life. While hundreds of such remains have been discovered so far, astronomers suspect thousands more are waiting in the wings.

The image allows them to distinguish between the gas surrounding new stars and the gas left behind, revealing clearer patterns in the cosmic landscape.

“You can clearly identify the remnants of exploded stars, represented by the large red circles. The smaller blue areas indicate stellar nurseries where new stars are actively forming,” Mantovanini said.

The image may also help unravel the mysteries of pulsars in our galaxy. By measuring the brightness of pulsars at different GLEAM-X frequencies, astronomers hope to gain a deeper understanding of how these mysterious objects emit radio waves and where they exist in our galaxy.

Associate Professor Natasha Hurley-Walker, from the same ICRAR team that is the principal investigator of the GLEAM-X survey, stressed that this is a big step forward in understanding the structure of the Milky Way.

“This low-frequency imaging allows us to reveal large astrophysical structures in our galaxy that are difficult to image at higher frequencies,” she said. “No low-frequency radio image of the entire southern galactic plane has been published before, making this an exciting milestone in astronomy.”

“Only the world's largest radio telescope, the SKA-Low telescope, scheduled for completion in the next decade in Wajarri Yamaji Country in Western Australia, will be able to surpass this image in terms of sensitivity and resolution,” concluded Associate Professor Hurley-Walker.

The research involved hundreds of hours of data collection using the MWA radio telescope located at Inyarrimanha Ilgari Bundara, CSIRO's Murchison Radio Astronomy Observatory. ICRAR researchers have cataloged an impressive 98,000 radio sources in the Galactic plane visible from the southern hemisphere, showing a diverse mix of pulsars, planetary nebulae, compact HII regions (which are dense clouds of ionized gas in space) and distant galaxies not related to the Milky Way.