A split-second burst of radio waves discovered by scientists using the Arecibo radio telescope in Puerto Rico provides important new evidence of mysterious pulses that appear to come from deep in outer space.

The finding, published in The Astrophysical Journal, is the first time that a "fast radio burst" has been detected by an instrument other than the Parkes radio telescope in Australia. Since the Parkes Observatory was the only telescope to previously pick up such events, scientists had speculated that it was merely detecting signals originating from sources on or near Earth.

"Our result is important because it eliminates any doubt that these radio bursts are truly of cosmic origin," lead author Victoria Kaspi, an astrophysics professor at McGill University in Montreal, said in a statement. "The radio waves show every sign of having come from far outside our galaxy - a really exciting prospect."

Scientists are still puzzled as to what exactly is causing these radio bursts. Possibilities include a range of exotic astrophysical objects, such as evaporating black holes, mergers of neutron stars, or flares from magnetars - a type of neutron star with extremely powerful magnetic fields.

"Another possibility is that they are bursts much brighter than the giant pulses seen from some pulsars," noted co-author James Cordes.

The bursts appear to be coming from beyond the Milky Way galaxy and occur roughly 10,000 times a day over the whole sky.

"The brightness and duration of this event, and the inferred rate at which these bursts occur, are all consistent with the properties of the bursts previously detected by the Parkes telescope in Australia," added Laura Spitler, who was involved in the study.

The discovery was made as part of the Pulsar Arecibo L-Band Feed Array (PALFA) survey, which aims to find a large sample of pulsars and to discover rare objects useful for better understanding neutron star physics and testing theories of gravitational physics.