Header Ads

A class of strange radio signals, first ‘live’ fast radio burst detected at Parkes Observatory


Mysterious radio signals detected by the Parkes telescope appear to come from an advanced civilization in the Milky Way. Unfortunately, it’s the one civilization we already know about.
Microwave ovens opened before they’re done cooking have been muddling the hunt for far more distant radio signals, researchers report online April 9 at arXiv.org. Astronomers have had to contend with enigmatic flares dubbed “perytons” ever since discovering equally puzzling fast radio bursts, or FRBs (SN: 8/9/14, p. 22), in 2007. Perytons and FRBs are quite similar, except that astronomers realized that perytons originate on Earth, possibly from some meteorological phenomenon, while FRBs come from other galaxies.
Three perytons in January coincided with independently detected blasts of 2.4 gigahertz radio waves — the same frequency that microwave ovens use to heat food. So researchers at the Parkes telescope in Australia spent weeks heating mugs of water while moving the massive radio dish around the sky, trying to re-create the phenomenon. Finally, researchers tried opening the oven door mid-cooking instead of letting the timer run out. Suddenly, perytons started showing up in the data.
The source of the galactic FRBs remain an intriguing mystery. Astronomers suspect they have something to do with imploding neutron stars or eruptions on magnetars. At this point, however, they might want to consider extraterrestrials nuking frozen pizzas.

Radio-, X-ray- and Visible Light

A team of astronomers in Australia developed a technique to search for these ‘fast radio bursts,’ so they could look for the bursts in real time. The technique worked, and now a group of astronomers, led by Emily Petroff (Swinburne University of Technology), have succeeded in observing the first ‘live’ burst with the Parkes telescope. The characteristics of the event indicated that the source of the burst was up to 5.5 billion light-years from Earth.
Now that they had the burst location and as soon as it was observed, a number of other telescopes around the world were alerted — both on the ground and in space — in order to make follow-up observations on other wavelengths.

 “Using the Swift space telescope we can observe light in the X-ray region, and we saw two X-ray sources at that position,” explains Daniele Malesani, astrophysicist at the Dark Cosmology Center, Niels Bohr Institute, University of Copenhagen.
Then the two X-ray sources were observed using the Nordic Optical Telescope on La Palma. “We observed in visible light and we could see that there were two quasars, that is to say, active black holes. They had nothing to do with the radio wave bursts, but just happen to be located in the same direction,” explains astrophysicist Giorgos Leloudas, Dark Cosmology Center, Niels Bohr Institute, University of Copenhagen and Weizmann Institute, Israel.

Further Investigation

So now what? Even though they captured the radio wave burst while it was happening and could immediately make follow-up observations at other wavelengths ranging from infrared light, visible light, ultraviolet light and X-ray waves, they found nothing. But did they discover anything?
“We found out what it wasn’t. The burst could have hurled out as much energy in a few milliseconds as the Sun does in an entire day. But the fact that we did not see light in other wavelengths eliminates a number of astronomical phenomena that are associated with violent events such as gamma-ray bursts from exploding stars and supernovae, which were otherwise candidates for the burst,” explains Daniele Malesani.
But the burst left another clue. The Parkes detection system captured the polarisation of the light. Polarisation is the direction in which electromagnetic waves oscillate and they can be linearly or circularly polarised. The signal from the radio wave burst was more than 20 percent circularly polarised and it suggests that there is a magnetic field in the vicinity.
“The theories are now that the radio wave burst might be linked to a very compact type of object — such as neutron stars or black holes and the bursts could be connected to collisions or ‘star quakes.’ Now we know more about what we should be looking for,” says Daniele Malesani.

No comments

Powered by Blogger.