Saturday, January 21, 2023

Hidden' supernova remnants in the Milky Way are found

Researchers from the Evolutionary Map of the Universe (EMU) and PEGASUS programs have combined the resources of both initiatives to study the enigma of: supernova remnants of the Milky Way: curiously, they were detected in an amount five times smaller than that predicted by models. As a result, they produced the most detailed radio image ever made of the Milky Way's galactic plane.

Supernova remnants are diffuse, expanding nebulae that, as the name implies, come from supernova explosions . Today, there are less than ten of them known, but astronomers estimate that there are 1,500 or even more of them waiting to be discovered. By studying them, scientists can better understand our galaxy's past.

To do so, the researchers combined observations from the Australian Square Kilometer Array Pathfinder (ASKAP) and Parkes/Murriyang radio telescopes, both from Australia. The new image reveals filaments and clouds associated with hydrogen gas filling the space between stars, also indicating where new stars form and, of course, supernova remnants. Despite showing just 1% of the entire Milky Way, the image revealed a new 20 candidate remnants.

The new findings suggest they are close to finding the “missing” ones as the models showed, and are a result of data from the EMU program. This is a project working with the ASKAP radio telescope to create the most complete radio atlas of the southern hemisphere sky. To do this, the members work with measurements of 40 million distant galaxies and supermassive black holes .

The images captured by ASKAP have good resolution, but lose radio emissions at larger scales. So, to recover lost information, project members turned to the PEGASUS project, which uses the Parkes/Murriyang telescope. Despite being one of the largest single-antenna radio telescopes in the world, it has limited resolution.

So, by combining the information from Parkes and ASKAP, the team was able to fill in the gaps left by the observatories, arriving at a high-fidelity image of the Milky Way region: PEGASUS captured a large part of the Milky Way's plane, and data from the ASKAP and Parkes can help with studies of the remnants with great accuracy.

“This combination reveals radio emissions at all scales to help us reveal supernova remnants, ” explains Andrew Hopkins, professor who leads the EMU program. He adds that summing up the EMU and PEGASUS datasets will help them reveal even more “hidden treasures”. “In the coming years, we will have an unprecedented view of almost the entire Milky Way, about a hundred times larger than this initial image, but with the same level of detail and sensitivity”, he concluded.

Source: Andrew Hopkins

 1_Supernova remnants are formed by the explosion of stars in a supernova (Image: Reproduction/NASA/CXC/GSFC/BJ Williams et al.;ESA/STScI)

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