Chapter 1: Introduction to the Enigma

Recent observations from the heart of the Milky Way have unveiled radio signals that defy existing astronomical knowledge. What could be the source of these mysterious emissions?

The ASKAP, or Australian Square Kilometre Array Pathfinder, has detected an extraordinary radio signal originating from the center of our galaxy. This phenomenon, designated ASKAP J173608.2–321635, exhibits fluctuations in intensity that vary a staggering 100 times between its peak and lowest points. Furthermore, the signals appear to turn on and off at seemingly random intervals, hinting at the possibility of a previously unidentified celestial object.

Professor Tara Murphy, from the Sydney Institute for Astronomy and the School of Physics, explains: “In our observations towards the center of the Galaxy, we identified ASKAP J173608.2–321635, named for its coordinates. Uniquely, this object was initially undetectable, then became luminous, faded, and re-emerged, showcasing unusual behavior.”

Join us on Astronomy News with The Cosmic Companion on November 2, where we will discuss this intriguing discovery with Professor Murphy!

Now You See It, Now You Don’t…

The ASKAP network comprises 36 advanced radio dishes equipped with state-of-the-art phased array feed receivers. Collectively, they generate over 100 trillion bits of data every second, surpassing the entire internet traffic in Australia.

After detecting the unusual signals over nine months in 2020, astronomers attempted to locate the source using optical telescopes, but their efforts yielded no results. Follow-up observations with the Parkes radio telescope also failed to confirm the unusual emissions.

“‘It’s silent. No vehicles. No birds. Nothing.’ ‘No radio waves,’ the Doctor said. ‘Not even Radio Four.’ ‘Can you hear radio waves?’ ‘Of course not. No one can,’ he replied, lacking conviction.” — Neil Gaiman

By utilizing the more sensitive MeerKAT radio telescope, researchers eventually regained contact with the elusive signal. However, unlike the initial observations where the signal persisted for weeks, it faded within just a day during the subsequent detection.

“Our monitoring with the MeerKAT telescope from November 2020 to February 2021 occurred on a 2-4 week schedule. The source was not detected prior to February 7, 2021,” the researchers noted in The Astrophysical Journal.

OK, Suppose It’s… Well, It’s Not THAT…

Deciphering the nature of these perplexing radio emissions has proven to be a complex challenge for astronomers.

“At first, we speculated it might be a pulsar—an extremely dense, spinning remnant of a star—or a type of star known for massive solar flares. However, the signals from this new source do not align with our expectations for these celestial categories,” states Ziteng Wang, a PhD student at the University of Sydney and lead author of the study on this discovery.

Moreover, just as light can be polarized when reflecting off surfaces like water or snow (which is why polarizing sunglasses are useful), the radio signals from ASKAP J173608.2–321635 also exhibit high polarization.

“The most intriguing feature of this new signal is its high degree of polarization, indicating that its light oscillates in a single direction that changes over time,” Wang elaborates.

The research team explored numerous theories regarding the origin of this strange signal. They concluded that ASKAP J173608.2–321635 could not be attributed to a low-mass star paired with an object that doesn't quite qualify as a star. Additionally, the hypothesis that the signal could be scattered light from a pulsar was also dismissed based on observational data.

“Our current knowledge aligns with another emerging category of enigmatic objects known as Galactic Centre Radio Transients (GCRTs), one of which is referred to as the ‘cosmic burper.’ While there are similarities between our object and GCRTs, significant differences persist. Since we have yet to fully comprehend those sources, this adds to the intrigue,” explains Professor David Kaplan from the University of Wisconsin-Milwaukee.

As future instruments, including the Square Kilometre Array (SKA), take to the skies, they may uncover answers to this mystery and perhaps introduce even more questions about the cosmos we inhabit.

James Maynard, founder and publisher of The Cosmic Companion, is a New England native now residing in Tucson with his wife, Nicole, and their cat, Max.

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Chapter 2: The Discovery of Radio Waves

The first video titled "Mysterious Radio Signal Discovered in Milky Way Center | What Is It!?" explores the implications of these newly discovered signals and their potential origins.

The second video titled "Gravitas: 'Strange' radio waves detected from the heart of the Milky Way" delves into the scientific community's response and ongoing research surrounding these mysterious radio waves.