Radio signal from space baffles scientists

A recently-detected radio signal from space mystifies scientists, who have no idea what it is or from where in the universe it originated.

The cosmic radio signal is a fast radio burst (FRB) – a burst of energy a billion times brighter than anything ever seen in the Milky Way galaxy. It is but one of 22 FRBs observed over the last decade, and they remain a mystery scientists are working hard to unravel.

Even pointing a telescope or other hi-tech instruments in the direction they came from has yielded no concrete answers – so it’s no surprise scientists have made little progress since the discovery of the first FRB in 2007. It’s possible they come from outside the galaxy. At least one FRB has been observed to repeat. They’re so mysterious that theories about their nature and origin range from extraterrestrial spacecraft to microwaves.

While 22 FRBs make the phenomenon seem rare, scientists are convinced these bursts occur frequently, with over 2,000 of them bringing illumination to the cosmos each day.

What makes them so hard to find is their extremely brief duration, which lasts an estimated 5 milliseconds. It was only early this year that researchers could confirm that FRBs aren’t the product of interference from Earth, but instead come from space.

The curious case of FRB 150215

So far this newest burst – which was named FRB 150215 after the date of its detection on February 15, 2015 by Australia’s Parkes Telescope – has proven the most puzzling. Even after scrutinizing the phenomenon using a variety of telescopes, the scientists are still no closer to figuring out what it means.

“We spent a lot of time with a lot of telescopes to find anything associated with it,” stated the study’s first author, the Netherlands Institute for Radio Astronomy’s Emily Petroff. “We got new wavelength windows we’ve never gotten before. We’re still trying to figure out where this one came from.”

Without a trace

While Petroff and her colleagues had no trouble viewing FRB 150215 through a number of telescopes worldwide, the burst left behind no trace of light. In fact, the scientists could not detect any sort of signal. Strange for something that produces the energy of as many as 500 million Suns.

“The burst was followed up with 11 telescopes to search for radio, optical, X-ray, gamma-ray, and neutrino emission,” said the scientists. “Neither transient nor variable emission was found to be associated with the burst, and no repeat pulses have been observed in 17.25 hours of observing.”

“I have to say this is a fantastic paper but it is a bummer of a paper,” said Shami Chatterjee, a Cornell Center for Astrophysics and Planetary Science senior research associate. “They threw every resource that we have at this FRB. They followed up with TNT, ANTARES, The Australian Telescope, Swift, Chandra, Magellan, the Dark Energy Camera, GMRT, Lovell, the VLA, and they see nothing. It is incredibly important in the sense that even with relatively prompt follow-up there isn’t an afterglow or counterpart that is obvious.”

Our experience with these FRBs is comparable to hearing a noise, turning around to identify the source and cause of the noise, only to find nothing even after searching 22 distinct places. In the case of FRB 150215, the researchers whirled around and used an enormous range of detection instruments – from Geiger counters to flashlights – all to no avail.

‘Some kind of hole’

Just as weird is how we were able to detect FRB 150215 – which should have been impossible from Earth. From its direction, the burst could have only reached us by passing through a region in the Milky Way galaxy possessed of extreme density.

By passing through such a dense region, FRB 150215 should have been influenced by severe magnetic interference, which in turn should have resulted in a high Rotation Measure (RM). Instead, the RM for FRB 150215 was a big fat zero.

“Surprising, because the FRB went through a dense line through the Milky Way, so there should be *some* RM!” tweeted Petroff.

According to Petroff, it’s possible the RM was zero because FRB 150215 “traveled through some kind of hole in the Milky Way that makes it easy to find compared to normal searches in the galaxy.”


Probably not aliens

Twenty-two is too small a sample size for scientists to know with any certainty where exactly these FRBs hail from.

Petroff does not, however, think advanced alien civilizations are behind the phenomenon.

“Just to be clear, we don’t know what is causing the fast radio bursts we see, but we don’t think it’s anything to do with aliens!” she tweeted.

Whatever the case may be, Petroff is simply happy to be a part of this new field of research.

“It’s not very often in science that you get to work on something that’s so brand new and so unknown that you get to answer the fundamental questions,” she stated. “It’s exciting to be in these very early stages of the field when you can make a big impact with your research and answer these really big questions.”

The published study is available at the pre-print website arXiv.org. — TJD, GMA News