A signal in the form of strange radio waves from the depth of the Milky Way is tantalizing researchers. Astronomers are now busy searching for more evidence to understand the source. Here’s what they know so far.
What are the strange radio waves?
Ziteng Wang, an international Ph.D. student at the University of Sydney observed unusual signals coming from the depth of the Milky Way using CSIRO’s ASKAP radio telescope. However, these strange radio waves do not fit any known pattern. Hence, astronomers believe that the signal may suggest the presence of a new stellar object. The strangest property of this new signal is that it is has a very high polarisation. This means its light oscillates in only one direction, but that direction rotates with time,” said Wang. Wang is the lead author of the novelle study. “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,” he added.
While several types of stars emit light, the variable objects in radio waves reveal the secrets of our Universe. “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,” said Wang. The new discovery is published in the Astrophysical Journal.
What do the signals mean?
The signals are studied by Wang and other international researchers from CSIRO, Canada, the US, Spain, France, and South Africa. The object was discovered with the ASKAP radio telescope, located in West Australia. Additionally, they are following them with observations from South Africa’s MeerKAT telescope. They detected six radio signals over a period of nine months. However, they could not find the object producing the signals. Similarly, MeerKAT could not reveal the source either.
“We have been surveying the sky with ASKAP to find unusual new objects with a project known as Variables and Slow Transients (VAST), throughout 2020 and 2021. Looking towards the center of the Galaxy, we found ASKAP J173608.2-321635, named after its coordinates. This object was unique in that it started out invisible, became bright, faded away, and then reappeared. This behavior was extraordinary,” said Professor Tara Murphy. Murphy is a researcher at the Sydney Institute of Astronomy and is Wang’s supervisor.
However, researchers are excited and will keep an eye out for the object. “Within the next decade, the transcontinental Square Kilometre Array (SKA) radio telescope will come online. It will be able to make sensitive maps of the sky every day. We expect the power of this telescope will help us solve mysteries such as this latest discovery, but it will also open vast new swathes of the cosmos to exploration in the radio spectrum,” added Murphy.