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The origin of powerful fast radio bursts (FRBs) – intense bursts of radio emission that last only a few milliseconds – have puzzled scientists since they were first detected just over a decade ago.
They are typically extragalactic, meaning they originate outside our galaxy, but on April 28 this year, multiple telescopes detected a bright FRB from the same area within our Milky Way.
Importantly, they were also able to locate the source: the galactic magnetar SGR 1935 + 2154. Magnetars, young neutron stars that are the most magnetic objects in the universe, have long been the prime suspects in the search for the source. of these radio bursts.
But this discovery marks the first time that astronomers have been able to trace the signal directly to a magnetar.
Christopher Bochenek, whose Survey for Transient Astronomical Radio Emission 2 (STARE2) in the United States was one of the teams to locate the explosion, said that in about a millisecond the magnetar emitted as much energy as the Sun’s radio waves in 30 seconds.
Watch: radio blast from inside the Milky Way
He said the burst was “so bright” that theoretically if you had a record of the raw data from your cell phone’s 4G LTE receiver and knew what to look for, “you may have found this signal that has come halfway across the galaxy” in the data. phone.
This energy was comparable to FRBs from outside the galaxy, he said, reinforcing the contention that magnetars were the source of most extragalactic explosions.
Up to 10,000 FRBs can occur each day, but these high-energy spikes were only discovered in 2007.
‘Active phase’
They have been the subject of heated debate since then, with even small steps towards identifying their origin that have sparked great enthusiasm for astronomers.
One problem is that momentary flashes are hard to spot without knowing where to look.
Theories about their origins range from catastrophic events such as supernovae, to neutron stars, which are super dense stellar fragments formed after a star’s gravitational collapse.
There are even more exotic explanations – taken for granted by astronomers – for extraterrestrial signals.
The latest discovery, which was published in three articles in the journal Nature, was made by pooling observations from space and ground-based telescopes.
Both STARE2 and the Canadian Hydrogen Intensity Mapping Experiment (CHIME) identified the glow and attributed it to the magnetar.
Later on the same day, this region of the sky came within sight of the highly sensitive Five Hundred Meter Aperture Spherical Telescope (FAST) in China.
Astronomers were already keeping an eye on the magnetar, which had entered an “active phase” and was emitting X-rays 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”
FAST didn’t locate the FRB itself, but it did detect multiple X-ray bursts from the magnetar, he said at a news conference, raising new questions about why only one of the flashes was connected to an FRB.
In a commentary on nature, Amanda Weltman and Anthony Walters, from the high-energy physics, cosmology and astrophysics theory group at the University of Cape Town, argued that linking the FRB to a magnetar “potentially solves a key puzzle. “.
But they said the findings also open up a host of new questions, including what mechanism would produce “such bright, but rare, radio bursts with X-ray counterparts?”
“A promising possibility is that a flare of a magnetar collides with the surrounding medium and thus generates a shock wave,” they wrote, adding that the results highlight the need for international cooperation in astronomy and monitoring of different types. of signals.
Kelly Macnamara © Agence France-Presse
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