Unusual signals emerging from the direction of the galactic center

A variable signal aligned to the heart of the Milky Way is tantalizing scientists.


Astronomers have discovered extremely polarized radio waves coming from the direction of the galactic center. The light from the waves oscillates in only one direction. But the strange thing is that direction rotates with time.

Thanks to advances in radio astronomy, astronomers are now able to reveal big mysteries of the Universe.

In this study, astronomers initially thought that the source of these radio waves could be a pulsar. But, the signals from this new source don’t match what is expected from these types of celestial objects.

There is dramatic variation in the object’s brightness, let’s say by a factor of 100. Also, the signal switches on and off apparently at random.

Zeng Wang, a lead author of the new study and a Ph.D. student in the School of Physics at the University of Sydney, said, “We’ve never seen anything like it.”

Professor Tara Murphy, also from the Sydney Institute for Astronomy and the School of Physics, said, “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 invisibly, became bright, faded away, and then reappeared. This behavior was extraordinary.”

Astronomers detected six radio signals from the source over nine months in 2020. When they tried finding the object in visible light, they found nothing. They also used the Parkes radio telescope but were unable to detect the source.

Then, they turned to the more sensitive MeerKAT radio telescope. To their surprise, they found the signal was intermittent. They observed it for 15 minutes every few weeks.

Professor Murphy said, “Luckily, the signal returned, but we found that the behavior of the source was dramatically different – the source disappeared in a single day, even though it had lasted for weeks in our previous ASKAP observations.”

Professor David Kaplan from the University of Wisconsin-Milwaukee said“The information we do have has some parallels with another emerging class of mysterious objects known as Galactic Centre Radio Transients, including one dubbed the ‘cosmic burper.'”

“While our new object, ASKAP J173608.2-321635, does share some properties with GCRTs, there are also differences. And we don’t understand those sources, anyway, so this adds to the mystery.”

Astronomers are now planning to keep an eye on the object to determine what exactly it is.

Journal Reference:
  1. Zeng Wang, David L. Kaplan et al. discovery of ASKAP J173608.2–321635 as a Highly Polarized Transient Point Source with the Australian SKA Pathfinder. DOI: 10.3847/1538-4357/ac2360
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