Fast radio burst from unknown source detected by astronomers in real time

Astronomers have observed an extremely short, sharp flash of radio waves from an unknown source in the universe. The mysterious phenomenon was detected, unlike in previous cases, right as it was happening.

The findings have been published in the Monthly Notices of the Royal Astronomical Society.

Since 2007, astronomers have observed a new phenomenon, a short burst of radio waves that lasted only a few thousandth of a second (milliseconds). It was first observed by accident in 2007, when scientists went through the archival data from the Parkes Radio Telescope in New South Wales, Eastern Australia.

Since then, six more such bursts have been reported in the Parkes telescope’s data. A seventh burst was discovered in the data from the world’s largest single-aperture telescope – the Arecibo telescope in Puerto Rico.

Short radio burst

The radio burst was intense and very short, only a few milliseconds. (Credit: Swinburne Astronomy Productions. Photo: University of Copenhagen)

Nearly all of them were discovered a long time after they occurred. Astronomers have since been trying to detect them right as they happen.

Detecting radio bursts in real time

An Australian team of astronomers developed a technique to search for these “Fast Radio Bursts” so that they could be observed in real time.

Their technique worked, and now a team, led by Emily Petroff, a PhD student in astrophysics at Swinburne University of Technology in Melbourne, Australia, has managed to observe the first “live” burst with the Parkes telescope.

Ms. Petroff said:

“These bursts were generally discovered week, months or even more than a decade after they happened. We are the first to catch one in real time.”

Parkes radio telescope

An illustration showing CSIRO’s Parkes radio telescope receiving the polarised signal from the new ‘fast radio burst’. (Credit: Swinburne Astronomy Productions)

According to data the astronomers gathered and analyzed, the burst came from somewhere in the universe 5.5 billion light years from Earth.

As soon as they detected the burst and had its location, they alerted several other telescopes around the world – on both ground and in space, in order to carry out follow-up observations on other wavelengths.

Daniele Malesani, an astrophysicist at the Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, said:

“Using the Swift space telescope we can observe light in the X-ray region and we saw two X-ray sources at that position.”

The Nordic Optical Telescope, located at Roque de los Muchachos Observatory, La Palma in the Canary Islands, was used to observe the two X-ray sources.

Giorgos Leloudas, an astrophysicist at the Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen and Weizmann Institute, Israel, said:

“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.”

Emily Petroff at the Parkes observatory

Emily Petroff at the Parkes observatory. (Image: Emily Petroff’s website)

Further investigation

So now what … did they discover anything? Even though the radio wave burst was captured while it was happening and follow-up observations at other wavelengths were made – including infrared light, visible light, ultraviolet light and X-ray waves – they found nothing.

Mr. Malesani explained:

“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.”

The burst did leave another clue. The Parkes detection system captured the polarization of the light, i.e. the direction in which electromagnetic waves oscillate (they can oscillate linearly or circularly polarized).

The radio wave burst’s signal was more than 20% circularly polarized, suggesting that there is a magnetic field in the vicinity.

Mr. Malesani said:

“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.”

Citation: A real-time fast radio burst: polarization detection and multiwavelength follow-up,” E. Petroff, M. Bailes, E. D. Barr, B. R. Barsdell, N. D. R. Bhat, F. Bian, S. Burke-Spolaor, M. Caleb, D. Champion, P. Chandra, G. Da Costa, C. Delvaux, C. Flynn, N. Gehrels, J. Greiner, A. Jameson, S. Johnston, M. M. Kasliwal, E. F. Keane, S. Keller, J. Kocz, M. Kramer, G. Leloudas, D. Malesani, J. S. Mulchaey, C. Ng, E. O. Ofek, D. A. Perley, A. Possenti, B. P. Schmidt, Yue Shen, B. Stappers, P. Tisserand, W. van Straten, and C. Wolf. Monthly Notices of the Royal Astronomical Society. (February 11, 2015) Vol. 447 246-255 doi:10.1093/mnras/stu2419 First published online January 19, 2015.

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