December 13, 2013
Fast Radio Bursts Might Originate From Within The Milky Way
redOrbit Staff & Wire Reports - Your Universe Online
Extremely quick, extremely bright radio pulses known as “fast radio bursts” may originate from flaring stars located within our own galaxy, researchers from the Harvard-Smithsonian Center for Astrophysics (CfA) claim in a new study.
Based on their characteristics, scientists had believed that these radio bursts came from galaxies located billions of light-years away. However, the pulses – which typically only last for one-thousandth of a second – “aren't as exotic as astronomers first thought,” lead author Avi Loeb said in a statement.
These phenomena are short-lived and exceptionally bright, packing a large amount of energy into a brief lifespan, the researchers explain. To date, only six have been discovered (all of them in archival data), and each of them have only been detected once. As such, follow-up studies on fast radio bursts have been rather hard to conduct.
“A detailed analysis of the bursts showed that the pulses passed through a large column of electrons on their way to Earth,” the Center explained. “If those electrons were spread out across intergalactic space, then the pulses must have crossed billions of light-years. As a result, they would have to come from extremely energetic events.”
Astronomers were able to eliminate gamma-ray bursts as a source, since they do not produce the correct radio frequencies, so Loeb and his colleagues considered other possible causes. They suggested that if the bursts had originated from a closer point of origin – one within our own galaxy – than less energy would be required.
“Stellar flares fit the bill. Tightly packed electrons in the stellar corona would cause the same effect as the more diffuse intergalactic electrons,” the CfA said. “Two types of stars are known to create radio bursts: young, low mass stars and solar-mass ‘contact’ binaries which orbit so close that they share their outer, gaseous envelopes. Both types of star system would also fluctuate in brightness at optical wavelengths (i.e. visible light).”
In order to test their theory, Loeb and his colleagues tracked down the location of three fast radio bursts in order to look for variable stars. With the help of investigators from Tel-Aviv University and telescopes from the institution’s Wise Observatory, they were able to monitor those fields for several nights, looking for unusual occurrences.
One of the locations was found to be home to a contact binary system, which consisted of two Sun-like stars orbiting each other approximately every eight hours. The binary system was located some 2,600 light-years from Earth, and statistics show that there is a less than five percent chance that it is in the right location by coincidence. Their findings will be published by Monthly Notices of the Royal Astronomical Society.
“Whenever we find a new class of sources, we debate whether they are close or far away,” Loeb said, noting that gamma-ray bursts were originally thought to be coming from within our galaxy, and that it was only later that experts found that they originated from outside the Milky Way. In this case, the opposite is true: fast radio bursts, believed to originate from great distances, might actually originate from within our own galaxy.