The influx of short bursts of radio signals has been baffling astronomers for years. However, a team of researchers may have finally found the source of the mysterious signals.
Illustration of signals from outer space reaching the Karl G. Jansky Very Large Array [Image by Danielle Futselaar]
Fast radio bursts (FRBs) occasionally ripple through space and into our sensors. These often come alone and last for just a fraction of a second. So far, about 30 FRBs have been discovered. However, one FRB, designated as FRB 121102, is the only one known to flash repeatedly though the others flash only once. Last year, just two scans that lasted 30 minutes each revealed 15 strange signals coming from a single source in a faraway dwarf galaxy.
As can be imagined, there have been a lot of suggestions as to what exactly may be the source of these signals. Some of suggested black holes, interstellar clouds, nebulae, or even aliens. However, new findings may soon lay these speculations about the source of FRB 121102 to rest.
The general area of the FRB 121102's origins
Though researchers have found the galaxy wherein the exact source of the signals lies, the actual source itself—as well as many other things about FRB 121102—are still unknown.
The research team that’s been monitoring FRB 121102 since they discovered it have recently found that the repeated radio bursts are polarized. According to the study, an effect called the “Faraday rotation” twists the signals as they shoot across a magnetic field. The Faraday rotation describes something similar to the way that polarized sunglasses handle bright light bouncing off of reflective surfaces. The strength of the signal waves’ twisting is directly proportional to the strength of the magnetic field.
"Here we see a twisting that is so extreme that it is almost unprecedented for an astronomical source of radio waves," said Jason Hessels, one of the researchers. "No other FRB source has shown the extreme "twisting" of the radio waves that FRB 121102 has shown us.”
These findings suggest that the signals travel through an intensely strong magnetic field, indicating that the source of the signals may be close to a massive black hole. Another possible explanation is that the source is nestled deep in a nebula or the remains of a supernova. However, researchers believe that a neutron star in a magnetic field is the source itself.
Illustration of a neutron star, the possible direct source of FRB 121102.
Neutron stars seem to make sense as the source of the signals, as far as the researchers are concerned. For one thing, when neutron stars behave as pulsars, they’re known to produce radio flashes. Also, the general rule is that the bigger an object is, the longer the radio signals it produces. Neutron stars are usually only about 19 kilometers across, making them great candidates as the provenance of FRB 121102. Furthermore, the polarization of these bursts are similar to the radio emissions of neutron stars in our very own Milky Way.
Still, this isn’t the last we’ll hear about FRB 121102. Hessels himself expects that other scientists will come up with their own papers offering different ideas on the same matter. This means that there are several possibilities as to what the source of the signals is, pushing the possibility that the source is extraterrestrial intelligence lower and lower on the list.
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