Radio Burst from within Milky Way May Help Solve Cosmic Mystery

According to research published Wednesday that sheds new light on one of the mysteries of the Universe, astrophysicists have observed a burst of cosmic radio waves inside our galaxy for the first time and identified its source.

Scientists have been confused by the sources of strong fast radio bursts (FRBs) — intense radio emission flashes that last just a few milliseconds — since they were first observed a little over a decade ago, reports AFP.

Usually, they are extragalactic, meaning they originate outside of our galaxy, but several telescopes observed a bright FRB within our Milky Way from the same location on April 28 this year.

Importantly, they were also able to pin down the source: SGR 1935 + 2154 galactic magnetar.

For a long time, magnetars, young neutron stars that are the most magnetic objects in the universe, have been prime suspects in search of the origins of these radio bursts.

But this discovery marks the first time that astronomers have been able to directly trace the signal back to a magnetar.

Christopher Bochenek, whose Transient Astronomical Radio Emission 2 (STARE2) Survey in the US was one of the teams to detect the burst, said that the magnetar released as much energy in about a millisecond as the Sun's radio waves in 30 seconds.

"He said the burst was" so vivid "that if you had a theoretical record of the raw data from the 4 G LTE receiver of your cell phone and knew what to search for," you might have noticed this signal in the phone data that came around halfway across the galaxy.

This energy was comparable to FRBs from outside the galaxy, he said, reinforcing the argument for most extragalactic bursts to be the source of magnetars.

As many as 10,000 FRBs may occur every day, but these high-energy surges were only discovered in 2007.

– ‘Active phase’ –

They have been the topic of heated debate ever since, with even small steps towards identifying their origin stirring major excitement for astronomers.

One problem is that the momentary flashes are difficult to pinpoint without knowing where to look.

Theories of their origins have ranged from catastrophic events like supernovas, to neutron stars, which are super-dense stellar fragments formed after the gravitational collapse of a star.

There are even more exotic explanation — discounted by astronomers — of extra-terrestrial signals.

The latest discovery, published in three articles in the journal Nature, was made by compiling observations from telescopes based on space and soil.

The flare was spotted by both STARE2 and the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and allocated to the magnetar.

Later that same day, the highly sensitive Five Hundred Meter Aperture Spherical Telescope (FAST) in China brought this area of the sky into view.

Astronomers there were already keeping an eye on the magnetar, which had entered an “active phase” and was firing off X-ray and gamma ray bursts, according to Bing Zhang, a researcher at the University of Nevada and part of the team reporting on the discovery.

– ‘Key puzzle’ –

He told a press conference that Quick did not spot the FRB itself, but it detected several X-ray bursts from the magnetar, posing new concerns about why only one of the bursts was related to the FRB.

Amanda Weltman and Anthony Walters, from the High Energy Physics, Cosmology and Astrophysics Theory Community at the University of Cape Town, said in a Nature Commentary that the relation between the FRB and a magnetar "potentially solves a crucial puzzle."

But they said the findings also open up a range of new questions, including what mechanism would produce “such bright, yet rare, radio bursts with X-ray counterparts?

“One promising possibility is that a flare from a magnetar collides with the surrounding medium and thereby generates a shock wave,” they wrote, adding that the findings highlight the need for international cooperation in astronomy and the monitoring of different types of signals.