Radio waves

Never-before-seen radio waves detected from nearby stars and distant galaxies

Scientists measured thousands of nearby stars and distant galaxies that had never before been identified at radio wavelengths, while studying a galactic body near ours Milky Way galaxy – the Large Magellanic Cloud.

Led by Keele University PhD student Clara M. Pennock and astrophysics reader Dr Jacco van Loon, the international team of researchers used Australia’s Square Kilometer Array Pathfinder (ASKAP) telescope to ‘photograph’ the cloud at radio wavelengths and study the star. structures inside, taking some of the clearest radio images of the Cloud ever recorded.

The Large Magellanic Cloud is a galaxy that borders ours, the Milky Way, and is known as a satellite dwarf spiral galaxy. It lies approximately 158,200 light-years from Earth and is home to tens of millions of stars.

Due to its proximity to the Milky Way, it is an excellent reference for researchers studying fundamental questions, such as star formation and the structure of galaxies.

The researchers not only took the sharpest radio images of the cloud ever recorded, but during their analysis they also studied the stars themselves that form the structure of the cloud, including the Tarantula Nebula, the region of the most active star formation of the local group. Additionally, newly detected radio emissions have also been studied from distant background galaxies as well as foreground stars in our own Milky Way.

This study, published in Royal Astronomical Society Monthly Notices, is part of the Evolutionary Map of the Universe (EMU) Early Science Project, which will observe the entire southern sky and is expected to detect around 40 million galaxies. The data will ultimately be used to give researchers a clearer picture of how galaxies and their stars have evolved over time.

Lead author Clara Pennock from Keele University said: “The sharp, sensitive new image reveals thousands of radio sources we’ve never seen before. Most of them are actually galaxies millions or even billions of light-years beyond the Large Magellanic Cloud. We usually see them because of the supermassive black holes in their centers which can be detected at all wavelengths, especially radio. But we are also starting to find many galaxies in which stars are forming at a breakneck pace. Combining this data with previous observations from X-ray, optical and infrared telescopes will allow us to explore these galaxies in extraordinary detail.

Dr Jacco van Loon, Reader in Astrophysics at Keele University, said: “With so many stars and nebulae clustered together, the increased sharpness of the image was instrumental in finding stars emitting radio and compact nebulae in the LMC. We see all kinds of radio sources, from individual infant stars to planetary nebulae that result from the death of stars like the Sun.

Co-author Professor Andrew Hopkins, from Macquarie University in Sydney, Australia, and EMU survey lead, added: “It is gratifying to see these exciting findings from early observations of EMU. EMU is an incredibly ambitious project whose scientific goals range from understanding the evolution of stars and galaxies to cosmological measurements of dark matter and dark energy, and much more. The findings from this early work demonstrate the power of the ASKAP telescope to provide sensitive images over large areas of the sky, offering a tantalizing glimpse of what the EMU’s comprehensive survey may reveal. This survey was key to enabling us to design the main survey, which is expected to start in early 2022.”

Reference: “The ASKAP-EMU Early Science Project: 888 MHz radio continuum survey of the Large Magellanic Cloud” by Clara M Pennock, Jacco Th van Loon, Miroslav D Filipović, Heinz Andernach, Frank Haberl, Roland Kothes, Emil Lenc, Lawrence Rudnick , Sarah V White, Claudia Agliozzo, Sonia Antón, Ivan Bojičić, Dominik J Bomans, Jordan D Collier, Evan J Crawford, Andrew M Hopkins, Kanapathippillai Jeganathan, Patrick J Kavanagh, Bärbel S Koribalski, Denis Leahy, Pierre Maggi, Chandreyee Maitra, Josh Marvil, Michał J Michałowski, Ray P Norris, Joana M Oliveira, Jeffrey L Payne, Hidetoshi Sano, Manami Sasaki, Lister Staveley-Smith and Eleni Vardoulaki, July 2, 2021, Royal Astronomical Society Monthly Notices.
DOI: 10.1093/mnras/stab1858

ASKAP is owned by the Commonwealth Scientific and Industrial Research Organization (CSIRO). ASKAP is an array of 36 satellite dishes with a greater separation of six kilometers, which when combined act as a telescope of approximately 4000 square meters.

ASKAP uses a new technique called phased array feeds (PAFs), and each of the 36 antennas has a PAF that allows the telescope to look at the sky in 36 directions at once, increasing the amount of sky that can be observed at once to 30 degrees squares on the sky and thus increase the survey speed.

ASKAP is a precursor to SKA, the world’s largest radio telescope, currently under construction in South Africa and Australia, and headquartered at Jodrell Bank Observatory near Manchester, UK.