Astronomers had already identified one type of magnetar with near certainty. So-called soft-gamma-ray repeaters (SGRs) emit sharp bursts of low-energy gamma rays and also bursts of X-rays. SGRs are thought to by a type of neutron star, a very dense object composed entirely of neutrons. Their intense bursts must be the result of strong magnetic fields, researchers say.

Another type of object that emits X-rays in periodic bursts is more enigmatic. For two decades, these so-called anomalous X-ray pulsars (AXPs) have befuddled researchers, who suspect these objects might also be magnetars. To explain an AXPs bursts, scientists assume the objects must be siphoning matter and energy from a companion star, storing it, then releasing it as the object's crust cracks in a manner similar to an earthquake.

Using data collected by the space-based Rossi X-ray Timing Explorer, the researchers found two X-ray bursts coming from the same direction as a known AXP called 1E1048.1-5937. The bursts are similar to bursts observed from SGRs.

"These events imply a close relationship (perhaps evolutionary) between AXPs and SGRs, with both being magnetars," the scientists conclude in their paper.

"It seems that magnetars do exist," says Shri Kulkarni of Caltech. "Astronomers can feel quite satisfied to have postulated, discovered and confirmed a new class of cosmic object."

Kulkarni was not involved in the new research but writes an analysis of it for Nature, adding that the results need to be confirmed with further research.

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