Fast radio bursts, also known as FRBs, are seemingly coming from everywhere in space these days, and astronomers are very curious as to why and what’s causing them.
Image Credit: Danielle Futselaar via Smithsonian
FRBs are essentially high-energy radio signals that can be detected from space with radio telescopes, but they’re hard to observe because they occur randomly and only last for a few milliseconds.
Because we’ve observed them from outer space fewer than 20 times and only just learned about them within the last decade, we still know little about them. We never really even knew what caused them. All we did know is that they appear to originate from high-energy sources in outer space naturally; possibly neutron stars.
Some of the most luminous FRBs ever recorded were discovered back in November and were among the only known FRBs ever to be observed. Despite what appears to be a rarity of outer space, it would seem that a particular location in outer space, the constellation of Auriga, is repeatedly sending these FRBs our way. It’s also the only known repeating FRB source.
A specific FRB discovered back in 2012 by the 305-meter radio telescope in Arecibo, Puerto Rico dubbed FRB 121102 is getting a lot of attention. Located in the constellation of Auriga, it has been the epicenter of FRB-related scientific studies for some time. One of the leading researchers of FRB activity is astronomer Shami Chatterjee of Cornell University.
“There are literally more theories for what FRBs are than there are detected examples of FRBs,” Chatterjee said in a statement to The Los Angeles Times. “It’s been a paradise for theorists; they’ve come up with all sorts of ways that you could produce these kinds of radio flashes.”
So, where are these FRBs actually coming from? While it’s hard to say for sure, observations from the Gemini Observatory in Hawaii have proven to be instrumental in helping to answer that question. There, researchers have reportedly pinpointed the main source of these FRBs, pointing to a faint galactic source anywhere from 2.5-3 billion light years away. The findings appear in the journal Nature.
This small galactic source only has about 1% of the mass of our Milky Way, so it’s nothing extravagant in terms of star formation. Nevertheless, this is the first major direct observation of the source of the FRBs, so it’s a start.
These findings are pretty important, as they answer some of the key questions about FRBs that have had researchers scratching their heads for some time. For example, we now know that they aren’t coming from our own galaxy, and we also know that they’re not cataclysmic because they’re repeating, which means the source is surviving long enough to be a repeat offender.
Radio emissions from young Neutron stars remain a possible explanation for their occurrence, but it’s nothing more than a theory at this point in time. Even if this was the case, the FRBs we're seeing are a lot brighter than we would expect them to be, so another theory comes to the table suggesting that perhaps hot plasma surrounding the young stars is working as some sort of lens and amplifying the FRB signals.
While one theory leads to another, the only way astronomers will ever get to the bottom of this is to observe more FRBs. Astronomers estimate that there could be as many as 10,000 FRBs in the skies at one time, but we have a very hard time detecting them hence why only a mere 18 have been officially recorded.
More questions we have yet to answer include why these FRBs only seem to happen so far away from us and how such immense energy required to travel nearly 3 billion light years is being produced, but those are questions for another day, when we have the chance to observe more of these FRBs.