A patch of space has been emitting fast radio bursts (FRB) for longer than previously thought possible. Now, it seems that scientists have finally figured out what causes these repeated signals.
While people love the idea of a possible extraterrestrial origin, a team of researchers suggests that the FRBs are generated by a dead star with a massive magnetic field.
According to the study published in the journal, Nature, a neutron star with a magnetic field as powerful as that of a massive black hole is responsible for the cosmic signals.
Fast radio bursts are intense pulses of radio waves that were previously thought to last a few milliseconds. During that very short amount of time, these pulses are able to give out energy that rivals our sun’s output over the course of hours, or even weeks.
The first signs of FRBs were discovered in 2007 and researchers estimate that such events can occur more than 10 thousand times a day across the entire sky.
What’s more interesting is that the origins of FRBs still remain a mystery, mainly due to the difficulty to pinpoint where they come from. A possible origin was thought to be from cataclysmic events like the collisions between neutron stars or the evaporation of black holes.
Since then, researchers have detected 18 FRBs which have been dubbed “flashes” or “sizzles”. In 2012, however, scientists discovered a radio burst cataloged as FRB 121102 which was able to emit approximately 150 flashes since it was discovered. In 2017, its host galaxy was identified as being a star-forming dwarf galaxy located at 3 billion light-years from Earth.
The latest readings made researchers realize that the fast radio bursts are polarized and their point of origin has an immensely strong magnetic field. These space radio signals had a higher frequency than any other FRB.
Radio waves that pass through a magnetic field are twisted, the process itself being called Faraday rotation. The twists are among the largest ever measured in a radio source.
“FRB 121102 was already unique because it repeats; now, the huge Faraday rotation we observed singles it out yet again.” Said Daniele Michilli, a PH.D. candidate at the University of Amsterdam and the Netherlands Institute for Radio Astronomy.
According to the researchers, there are two possible causes for these strong magnetic fields. One would be the proximity to a massive black hole or the source is coming from within a powerful nebula. While the two theories do explain some aspects of the FRBs, they also raise a few other questions.
If the source is near a black hole, that would explain the frequent bursts, however, the researchers are skeptical that a black hole of this magnitude would exist in a dwarf galaxy.
Being inside a nebula would also explain its persistent radio bursts, yet the interstellar cloud formation is brighter than our own Crab nebula, which itself is already massively bright.
Researchers believe that the source of the FRBs might be either a neutron star or a magnetized rotating neutron star, commonly known as a pulsar.
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