Strange radio waves emerge from the direction of the galactic cente

Strange radio waves emerge from the direction of the galactic center

by University of Sydney

Artist's impression of radio signal ASKAP J173608.2-321635 arriving at Earth. Credit: Sebastian Zentilomo/University of Sydney

Astronomers have discovered unusual signals coming from the direction of the Milky Way's center. The radio waves fit no currently understood pattern of variable radio source and could suggest a new class of stellar object.

"The strangest property of this new signal is that it is has a very high polarization. This means its light oscillates in only one direction, but that direction rotates with time," said Ziteng Wang, lead author of the new study and a Ph.D. student in the School of Physics at the University of Sydney.

"The brightness of the object also varies dramatically, by a factor of 100, and the signal switches on and off apparently at random. We've never seen anything like it."

Many types of star emit variable light across the electromagnetic spectrum. With tremendous advances in radio astronomy, the study of variable or transient objects in radio waves is a huge field of study helping us to reveal the secrets of the Universe. Pulsars, supernovae, flaring stars and fast radio bursts are all types of astronomical objects whose brightness varies.

"At first we thought it could be a pulsar—a very dense type of spinning dead star—or else a type of star that emits huge solar flares. But the signals from this new source don't match what we expect from these types of celestial objects," Mr Wang said.

The discovery of the object has been published today in the Astrophysical Journal.

Mr Wang and an international team, including scientists from Australia's national science agency CSIRO, Germany, the United States, Canada, South Africa, Spain and France discovered the object using the CSIRO's ASKAP radio telescope in Western Australia. Follow-up observations were with the South African Radio Astronomy Observatory's MeerKAT telescope.

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Artist's impression of the oscillating, variable radio signal ASKAP J173608.2-321635 arriving at Earth from towards the centre of the Milky Way. Credit: Sebastian Zentilomo/University of Sydney

Mr Wang's Ph.D. supervisor is Professor Tara Murphy also from the Sydney Institute for Astronomy and thhttps://phys.org/news/2021-10-strange-radio-emerge-galactic-centre.html?fbclid=IwAR3h3umEuEVxs2t3PQ6ynVptUJq72Cz3fN6Cq5d45hknl58swhg3BguteUke School of Physics.

Professor Murphy said: "We have been surveying the sky with ASKAP to find unusual new objects with a project known as variables and slow transients (VASTs), throughout 2020 and 2021.

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