Insights from recent posts in The Galaxy on fast radio bursts (FRBs) are one of the most baffling mysteries of the cosmos by several of the world’s leading astronomers and physicists.
Fast radio bursts (FRBs) are among the most enigmatic and powerful events in the cosmos. Around 80 of these events–intensely bright millisecond-long bursts of radio waves coming from beyond our galaxy–have been witnessed so far, but their causes remain unknown. Despite happening frequently – thousands occur over the entire sky every day – only a couple dozen FRBs have ever been seen. Scientists don’t know what causes them but it must involve incredible energy–equivalent to the amount released by the Sun in 80 years.
“We still have no new clue on whether the origin is artificial or natural,” said Harvard astronomer Avi Loeb about fast radio bursts (FRBs), one of the great astrophysical mysteries. In a rare feat, Caltech researchers have caught a new burst, called FRB 190523, pinpointing its origins to a galaxy 7.9 billion light-years away.
In a 2018 study, Harvard’s Loeb had examined the possibility that fast radio bursts come from radio transmitters constructed by an advanced alien civilization — perhaps evidence of powerful energy beams used to propel alien starships. He also theorized that repeater sources are more likely to be such alien signals because natural origin explanations would most likely produce only a single burst.
Loeb and colleague Manasvi Lingam at Harvard University examined the feasibility of creating a radio transmitter strong enough for it to be detectable across such immense distances. They found that, if the transmitter were solar powered, the sunlight falling on an area of a planet twice the size of the Earth would be enough to generate the needed energy. Such a vast construction project is well beyond our technology, but within the realm of possibility according to the laws of physics.
“Finding the locations of the one-off FRBs is challenging because it requires a radio telescope that can both discover these extremely short events and locate them with the resolving power of a mile-wide radio dish,” says Vikram Ravi, a new assistant professor of astronomy at Caltech who works with the radio telescopes at OVRO, situated east of the Sierra Nevada mountains in California, focusing on exploring the ephemeral, unseen Universe.
FRBs can be used to study the amount and distribution of matter in our universe, which will tell us more about the environments in which galaxies form and evolve. As radio waves from FRBs head toward Earth, intervening matter causes some of the wavelengths to travel faster than others; the wavelengths become dispersed in the same way that a prism spreads apart light into a rainbow. The amount of dispersion tells astronomers exactly how much matter there is between the FRB sources and Earth.
“Most matter in the universe is diffuse, hot, and outside of galaxies,” says Ravi. “This state of matter, although not ‘dark,’ is difficult to observe directly. However, its effects are clearly imprinted on every FRB, including the one we detected at such a great distance.”
New research provides clues that magnetars, lying in close proximity to a black hole, could perhaps be linked to the source of “fast radio bursts,” or FRBs. FRBs are high-energy blasts that originate beyond our galaxy but whose exact nature is unknown. They appear to come from extreme high-energy objects, but because they last just a few milliseconds, their origin remains a profound mystery.
Magnetars are thought to be young pulsars that spin more slowly than ordinary pulsars and have much stronger magnetic fields, which suggests that perhaps all pulsars go through a magnetar-like phase in their lifetime.
The Daily Galaxy, Max Goldberg via The Guardian