Mysterious radio signals emitting from outer space are not from aliens after all, according to new research.
First discovered in 2007, the strange beams are known as fast radio bursts (FRBs) – and last only a millisecond.
Some experts have suggested they may from an extraterrestrial life form trying to contact Earth.
A new study by Japanese scientists has come up with a far less fanciful theory to explain mystery signals: starquakes.
The exact cause and origins of FRBS are still unconfirmed.
The intense bursts of radio energy are invisible to the human eye, but show up brightly on radio telescopes.
Previous studies have noted broad similarities between the energy distribution of repeat FRBs, and that of earthquakes and solar flares.
Researchers at the University of Tokyo have looked at the time and energy of FRBs and found “distinct” differences between FRBs and solar flares, but several notable similarities between FRBs and earthquakes.
Their findings, published in the journal Monthly Notices of the Royal Astronomical Society, support the theory that FRBs are caused by “starquakes” on the surface of neutron stars.
The team say the discovery could help us better understand earthquakes, the behavior of high-density matter and aspects of nuclear physics.
Neutron stars form when a supergiant star collapses, going from eight times the mass of our sun, on average, to a superdense core only around 25 miles across.
Magnetars are neutron stars with extremely strong magnetic fields, and these have been observed to emit FRBs.
Professor Tomonori Totani said: “It was theoretically considered that the surface of a magnetar could be experiencing a starquake, an energy release similar to earthquakes on Earth.
“Recent observational advances have led to the detection of thousands more FRBs, so we took the opportunity to compare the now large statistical data sets available for FRBs with data from earthquakes and solar flares, to explore possible similarities.”
So far, statistical analysis of FRBs has focused on the distribution of wait times between two successive bursts.
However, Prof Totani and co-author Yuya Tsuzuki, a graduate student, point out that calculating only the wait-time distribution does not take into account correlations that might exist across other bursts.
The team decided to calculate correlation across two-dimensional space, analyzing the time and emission energy of nearly 7,000 bursts from three different repeater FRB sources.
They then applied the same method to examine the time-energy correlation of earthquakes, using data from Japan, and of solar flares, and compared the results of all three phenomena.
The researchers were surprised that, in contrast to other studies, their analysis showed a striking similarity between FRBs and earthquake data, but a distinct difference between FRBs and solar flares.
Prof Totani said: “The results show notable similarities between FRBs and earthquakes in the following ways:
“First, the probability of an aftershock occurring for a single event is 10 to 50 per cent; second, the aftershock occurrence rate decreases with time, as a power of time; third, the aftershock rate is always constant even if the FRB-earthquake activity changes significantly.
“And, fourth, there is no correlation between the energies of the main shock and its aftershock.
“This strongly suggests the existence of a solid crust on the surface of neutron stars, and that starquakes suddenly occurring on these crusts releases huge amounts of energy which we see as FRBs.”
The team intends to continue analysing new data on FRBs, to verify that the similarities they have found are universal.
Prof Totani added: “By studying starquakes on distant ultradense stars, which are completely different environments from Earth, we may gain new insights into earthquakes.
“The interior of a neutron star is the densest place in the universe, comparable to that of the interior of an atomic nucleus.
“Starquakes in neutron stars have opened up the possibility of gaining new insights into very high-density matter and the fundamental laws of nuclear physics.”
It is estimated that up to 10,000 FRBs may happen every day if we could observe the whole sky.
While the sources of most bursts detected so far appear to emit a one-off event, around 50 FRB sources emit bursts repeatedly.
Produced in association with SWNS Talker
