Researchers have captured the faint echo of a powerful radio wave burst coming from a colossal galactic merger that dating to about 8 billion years ago. This event marks the detection of the oldest-known instance of a phenomenon called a fast radio burst that continues to defy explanation.

The fleeting burst, lasting a mere millisecond, unleashed the amount of energy equivalent to our sun emits over three entire decades. It was initially detected by the Australian SKA Pathfinder radio telescope. The European Southern Observatory’s Very Large Telescope (VLT) in Chile subsequently pinpointed its precise location with remarkable accuracy.

A fast radio burst, or FRB, is a pulse of radio-frequency electromagnetic radiation. It lasts a small fraction of a second but outshines most other sources of radio waves in the universe. Radio waves have the longest wavelengths in the electromagnetic spectrum.

In a recent study published in the esteemed journal Science, Dr. Ryan Shannon, astronomer at Swinburne University of Technology (Australia) and co-leader of the research team, explains the nature of the FRB’s radio waves. “These radio waves share remarkable similarities with those employed in common microwave ovens,” he states. “The sheer amount of energy unleashed in this particular FRB is akin to microwaving a bowl of popcorn, double the size of our sun!”

Prior to this discovery, the most ancient FRB  dated to 5 billion years ago. This newfound champion surpasses its predecessor by 3 billion years. The universe is about 13.8 billion years old. For comparison, Earth is about 4.5 billion years old. In seeing objects and events from long ago, astronomers peer across vast cosmic distances, making this burst also the farthest of any FRB ever detected.

“This discovery compels us to acknowledge that FRBs have been a prevalent phenomenon for over half the universe’s existence,” remarks Dr. Stuart Ryder, co-leader of the study and affiliated with Macquarie University (Australia). The enigmatic FRBs were first identified in 2007.

The leading theory pinpoints hyper-magnetized neutron stars, known as magnetars, as the prime suspects for FRB production. “These stellar remnants boast the mass of our sun, condensed into a city-sized package,” elaborates Dr. Shannon. “They rank among the most extreme objects in the cosmos, a characteristic necessary to generate such extraordinary bursts.”

“While the universe harbors more energetic events, such as stellar explosions or a black hole ripping a star apart, FRBs hold a unique distinction,” Dr. Shannon continues. “They concentrate their entire energetic output within the radio wave spectrum, leaving no traces in other bands like visible light or X-rays. Additionally, their signals are incredibly short-lived.”

They also are more common, with estimates suggesting upwards of 100,000 potentially erupting across the cosmos each day. However, only a minuscule fraction have been successfully detected, and a mere 50 or so (including this latest discovery) have been traced back to their galactic origins.

“Galaxies in the distant universe exhibit a distinct appearance compared to their nearby counterparts,” explains Dr. Shannon. “They lack the well-defined spiral arms we observe in our own Milky Way. This ambiguity made it challenging to discern whether we were witnessing a single galaxy with clumps or a conglomeration of smaller galaxies. The prevailing theory suggests the source is likely a merger of several galaxies.”

The research team underscores the significance of FRB studies in uncovering and quantifying the vast reservoirs of matter believed to permeate the intergalactic voids. As these radio waves zip through the cosmos, they interact with this intergalactic plasma, a scorching hot gas where atoms are stripped bare, leaving behind a sea of electrons and ions.

“Most of the normal matter in the universe – this is the regular matter that makes up stars, planets, humans – is thought to reside in a diffuse cosmic web of gas between galaxies,” Shannon said. “People have been searching for this matter for decades using other techniques. Because it is so diffuse, it is nearly invisible in any other way, so was considered ‘missing.'”

This discovery presents astronomers with a new window into the early universe and the potential progenitors of FRBs. Further research into these ancient bursts will undoubtedly enhance our understanding of these cosmic enigmas.

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