Astronomers detect mysterious intergalactic radio bursts

July 05, 2013

Astronomers detect mysterious intergalactic radio bursts

Similar signals have been detected before, but this is the first time that scientists have been able to definitively identify their origins as outside of the Milky Way.

While looking through archived sky sweeps completed by the Parkes radio telescope in New South Wales, Australia, astronomers discovered mysterious intergalactic radio bursts; powerful signals removed from the galactic plane and originating from different spots in the sky.

Because the data was archived and the bursts so sporadic, the scientists have no way of following up on the oddity, Discovery News reports. Later analysis of the bursts indicated that they do not seem to have originated from within our own Milky Way galaxy, but from beyond.

Amazingly, in just a few milliseconds, each burst released around the same amount of energy that the sun releases in 300,000 years. Scientists have a bevy of theories as to what triggered the bursts, including colliding magnetars, evaporating black holes and gamma ray bursts involving a supernova.

Any of these unusual space phenomenon could have caused the bursts, but it is difficult for scientists to determine the exact origins of the bursts. The bursts could also be coming from an intergalactic event that has yet to be discovered. In other words, something entirely new to astronomers.

Scientists estimate that these occurrences are not rare, but that they are rarely detected. They estimate that about 10, 000 similar bursts happen every day. Telescopes only look at one small piece of the sky at any given time, making observing a large quantity of these bursts impossible. An observer would have to look for a very long time before seeing many, and even with the ability to record the data and review it at a later date it is still difficult to observe a large swath of the sky.

Similar signals have been detected before, but this is the first time that scientists have been able to definitively identify their origins as outside of the Milky Way. Astronomer Dan Thornton, with the University of Manchester in the United Kingdom, and his team were able to identify the origin of the bursts by analyzing and characterizing the plasma that the radio waves traveled through before reaching the telescope.

“The bursts’ properties indicate that they are of celestial rather than terrestrial origin. Host galaxy and intergalactic medium models suggest that they have cosmological redshifts of 0.5 to 1 and distances of up to 3 gigaparsecs. No temporally coincident x- or gamma-ray signature was identified in association with the bursts,” the researchers wrote in the study’s abstract.

The amount of plasma in the path of the wave determines and defines its shape. Through this method, Thornton discovered that the waves must have traveled through more plasma than would have been possible simply within the Milky Way galaxy. Thus, they likely came from beyond. The team suspects that the interstellar gas the waves would have traveled through is located between galaxies. This information opens a door to new research using a novel technique to analyze the contents of distant galaxies, as well as what lies between them.

“Characterization of the source population and identification of host galaxies offers an opportunity to determine the baryonic content of the universe,” the researchers noted.


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