Some achive information from an Australian radio telescope has come with a surprising discovery: a strong, short-lived burst of radio waves betraying a new class of astronomical phenomenon.
"This burst appears to have originated from the distant Universe and may have been produced by an exotic event such as the collision of two neutron stars or the death throes of an evaporating black hole," said lead researcher Duncan Lorimer, Assistant Professor of Physics at West Virginia University (WVU) and the National Radio Astronomy Observatory
The finding was made by a WVU undergraduate student David Narkevic while re-analyzing information from 480 hours of observations of the Small Magellanic Cloud realized by the 210-foot Parkes radio telescope in Australia. "This survey had sought to discover new pulsars, and the data already had been searched for the type of pulsating signals they produce. We re-examined the data, looking for bursts that, unlike the usual ones from pulsars, are not periodic", said Lorimer.
The Magellanic Clouds are a couple of small galaxies neighboring the Milky Way Galaxy at 200,000 light-years from Earth. Still, the new discovery is not part of the Magellanic Clouds, but much more remote.
By sheer luck, "flanking" observations revealed the enigmatic recorded radio bursts, powerful but extremely short lived: less than 5 milliseconds. The signal was dispersed, higher frequencies being captured by the telescope before the lower ones. This meant the waves crossed ionized gas in interstellar and intergalactic space, and the quantity of dispersion points to an origin place about 3 billion light-years from Earth. "This burst represents an entirely new astronomical phenomenon. The astronomers estimate on the basis of their results that hundreds of similar events should occur over the sky each day.", said co-author Matthew Bailes of Swinburne University in Australia.
"Few radio surveys have the necessary sensitivity to such short-duration bursts, which makes them notoriously difficult to detect with current instruments," explained co-author Fronefield Crawford of Franklin and Marshall College in Lancaster, Pennsylvania.
Future radio telescopes could pick many of these bursts. But for now, their origin is unknown: some say they could be released by the collision of two superdense neutron stars, explaining the presence of a particular gamma-ray; still, the radio emission detected so far comes from the long-lived "afterglow", following the original burst.
Another theory explains the formation of such waves by the evaporating black hole. The mass and energy losses of the black holes have been signaled even by Stephen Hawking. These radio bursts could be the "last gasp" of a black hole as it finishes completely. "We're actively looking for more of these powerful, short bursts, in other archival pulsar surveys, and hope to resolve the mystery of their origin. In addition, if we can associate these events with galaxies of known distance, the radio dispersion we measure can be used as a powerful new way to determine the amount of material in intergalactic space", said co-author Maura McLaughlin of WVU.