New X-ray and radio observations detected a strange switcheroo in the radiation from a pulsar.

Pulsars are like zombie stars. They’re stellar corpses called neutron stars, left over from massive stars’ explosive deaths. But like zombies, pulsars have a second life in them: instead of decaying quietly, these highly magnetized objects send beams into space that radiate away the energy of their whirligig spins. They’re like lighthouses on steroids — well, undead lighthouses on steroids.

A new paper in the January 25th Science reports new observations that suggest pulsars might be ever weirder than astronomers thought. I know it’s hard to imagine something weirder than a zombie lighthouse, but X-ray and radio observations of a pulsar with a penchant for radio hiccups show that, contrary to expectation, the pulsar’s X-ray emission switches on and off, just like the radio emission — except that it does it in reverse: when the radio emission is “bright” the X-rays are not, and vice versa.

The ESA put out a really thorough press release on the result, which I recommend reading. As the release explains, the new observations raise questions about how these emissions are created and, more importantly, linked. It looks like big, fast upheavals happen in the pulsar’s magnetic bubble. But as Wim Hermsen (Netherlands Institute for Space Research and University of Amsterdam, the Netherlands) and his colleagues say in their paper, the whole thing is a big mystery.

ESA RELEASE:

Baffling pulsar leaves astronomers in the dark

New observations of a highly variable pulsar using ESA's XMM-Newton are perplexing astronomers. Monitoring this pulsar simultaneously in X-rays and radio waves, astronomers have revealed that this source, whose radio emission is known to 'switch on and off' periodically, exhibits the same behaviour, but in reverse, when observed at X-ray wavelengths. It is the first time that a switching X-ray emission has been detected from a pulsar, and the properties of this emission are unexpectedly puzzling. As no current model is able to explain this switching behaviour, which occurs within only a few seconds, these observations have reopened the debate about the physical mechanisms powering the emission from pulsars. . . . Read the full press release.