Saturday, October 16, 2021, 08:00 – These spiral signals flashed in an unprecedented way, leaving astronomers with a lot of mystery in their hands.
Some mysterious objects in the depths of our galaxy emit a strange pattern of radio waves, unlike ever before. This made the astronomers who discovered it wonder if they had discovered something completely new for us.
Astronomers use radio telescopes to scan the sky for signs of change. The stars may seem to shine as you watch them from Earth, but most of them are very stable and unchanging (it is the Earth’s atmosphere that makes them flash). But some things change in brightness over time. Astronomers call them “variables.” Other things appear and disappear. These are known as “temporary”. Discovering these objects and events can lead to a deeper understanding of how the universe works.
The Milky Way is the nucleus of our galaxy. Credit: Risinger / Guisard / ESO / Hubble
The Variable and Slow Pass (VAST) survey has been scanning the skies since early 2020 using Australia’s Square Kilometer Array Pathfinder (ASKAP) radio telescope system.
Professor Tara Murphy, one of the co-authors of the new study from the University of Sydney, said, “Looking at the center of the galaxy, we found ASKAP J173608.2-321635, called the coordinates.” “This object was unique in that it started invisible, shone, faded, and then reappeared. This behavior was unusual.”
Between January and September 2020, intermediate signals from ASKAP J173608.2-321635 appeared only six times.
The source of these strange radio signals is depicted in this composite radio image from both ASKAP and the MeerKAT radio telescope in South Africa. Credit: Ziteng Wang, et al.
“The brightness of the object changes 100 times and the signal turns on and off accidentally. We have never seen anything like it,” said Dr. Ziteng Wang. the student leading the research.
The intermediate nature of the radio waves emanating from this object is at least strange. Even more bizarre is how radio waves “spiral” in space.
“The strangest feature of this new signal is that it has a very high polarization. It means that its light is emitted in only one direction, but this direction rotates over time,” Wang said.
This artist’s impression shows that intermediate radio signals from ASKAP J173608.2-321635 are circulating in space. Credit: Sebastian Zentilomo
“Polar radio sources are extremely rare,” Wang, Murphy and co-author David Kaplan wrote in an article about The Conversation this week. “We can find fewer sources of it in thousands of circular sources. Almost all of them are well-understood sources, such as pulsars (highly magnetized remnants of fast-rotating, exploding stars) or highly magnetized red dwarf stars.”
For now, the essence of ASKAP J173608.2-321635 remains a mystery. Other radio telescopes did not pick up radio ticks that did not look like pulsar radios, so they are not the remains of a dead star. Also, no object has been detected by visible light or infrared telescopes, so the red dwarf is not a star.
The Australian Square Kilometer Array Pathfinder (ASKAP) consists of 36 radio dishes located in the countryside of Western Australia. Credit: CSIRO
There is another object type that has similarities with ASKAP J173608.2-321635. Because of their proximity to the Milky Way nucleus, they are known as Galactic Central Radio Transitions (GCRTs). Regardless, there are significant differences that GCRTs do not provide an adequate explanation.
“And we don’t really understand these sources,” Professor Kaplan said, “so this mystery is added.”
For now, they will continue to gather more observations from this source and others, hoping to solve the mystery.