The Signals from the Milky Way

The structure of the universe is a very important astronomical topic that you learn in every base level astronomy class. First, there are planets, then stars, galaxies, galaxy clusters, galaxy superclusters, and finally, the observable universe. Today, we are stopping at galaxies and talking about our home, the Milky Way galaxy. The Milky Way Galaxy is HUGE! The Milky Way Galaxy has a diameter of 180,000 light years and has approximately 400 billion stars which is insane. It houses billions of solar systems. But some strange signals were detected 27,000 light years away at the center of the Milky Way Galaxy.

Picture of Milky Way Taken by
Chandra X-Ray Observatory

A new paper published in the Astrophysical Journal said that the energy source that the radio signals originated from is a unique and very finicky energy source. Why finicky you might ask: the radio signals were coming in a very distinct pattern for weeks at a time and then all of a sudden, just stopped. This profile of radio waves didn’t fit any celestial bodies on record and perplexed researchers. They concluded that the radio waves were coming from a new class of objects!

ASKAP Radio Telescope

The new radio source - now known as ASKAP J173608.2-321635 - was detected by the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope. Between April 2019 and August 2020, the ASKAP detected this strange radio signal 13 times. From these observations, the team noticed that there was no pattern and that this radio signal hadn’t been observed by anyone else. The team then tried to observe what they were seeing on different telescopes such as the Chandra X-ray Observatory and the Neil Gehrels Swift Observatory, but were not able to locate it using them. 

So what could it be. One theory is a low-mass star in the center of the Milky Way. Prior observation has shown that low-mass stars can flare up with radio energy. However, those flaring stars have X-ray counterparts, which defeats the low-mass star theory. Another theory was dead stars like pulsars and magnetars which are both ultradense collapsed stars. However, this theory also isn’t the strongest because both pulsars and magnetars radio and X-ray signals didn’t match with the detected signals. The closest thing that we know that may be the source of these radio signals: the galactic center radio transient (GCRT). The GCRT is a radio source that brightens and decays near the Milky Way’s center over the course of a few hours. However, there are only 3 known GCRTs and they often disappear faster than the object discovered. But mathematical models and other GCRTs in the universe have shown this behavior.

So what is the object? Scientists believe that it is a new type of GCRT, but that isn’t known for sure. For all we know, it could be some alien race that is having an out of this world rock concert.

Image of GCRT J1745-3009 

Sources:

“Australian Square Kilometre Array Pathfinder.” Wikipedia, Wikimedia Foundation, 28 July 2021, en.wikipedia.org/wiki/Australian_Square_Kilometre_Array_Pathfinder. 

“GCRT J1745−3009.” Wikipedia, Wikimedia Foundation, 6 Aug. 2021, en.wikipedia.org/wiki/GCRT_J1745%E2%88%923009. 

“Milky Way.” Wikipedia, Wikimedia Foundation, 10 Sept. 2021, en.wikipedia.org/wiki/Milky_Way#Size_and_mass. 

Specktor, Brandon. “Strange, Repeating Radio Signal near the Center of the Milky Way Has Scientists Stumped.” Space.com, Space, 9 Sept. 2021, www.space.com/strange-radio-source-milky-way-center.