Neutron stars rival black holes' jet power
Black holes, long thought to be the Universe's unrivalled producer of powerful jets of material blasting into space, could have a new rival in the form of neutron stars.
An artist's impression of binary star system PSR J1023+0038, depicting the neutron star pulling gas from its companion and launching powerful jets into space. Credit: ICRAR
A neutron star has been observed shooting out jets of material with enough power to rival those of black holes.
The discovery suggests black holes are not the only objects in the Universe capable of forming jets with such ferocity.
Double star system PSR J1023+0038 contains a neutron star in close orbit with a more normal star.
Neutron stars are formed when a massive star undergoes a supernova and its centre collapses under its own gravity.
They are usually 1.5 times the mass of the Sun, yet are only as big as 10-15km across.
This makes them one of the densest objects in the Universe, second only to black holes.
Both are known to exist in binary systems with a companion star, whereby gas flows from the companion to the black hole or neutron star and produces powerful jets blasting into space at almost the speed of light.
ASTRON astronomer Adam Deller, who led the study that discovered the neutron’s powerful jets, says:
“From what we had seen previously, black holes were previously considered the undisputed kings of forming powerful jets, even when they were only fed by a little bit of material from their companion star.
“In comparison, neutron stars seemed to make relatively puny jets, which only became bright enough to see when the neutron stars were gobbling gas from their companions at a very high rate.”
When the team first looked at the star system, it was only consuming a small amount of material and should have been producing only a weak jet.
But combined radio and X-ray observations of the neutron star showed that this is not the case.
“Our observations suggest its jets are nearly as strong as you’d expect from a black hole,” says Deller.
“It’s surprising, and it tells us that something we hadn’t previously suspected must be going on in some systems that include a neutron star and a more normal companion star.”
PSR J1023+0038 is a ‘transitional’ system that spends years at a time powered mostly by the rotation of the neutron star.
Sometimes it transitions into an active gathering state and becomes much brighter.
Two other ‘transitional’ systems are now known since PSR J1023+0038 was discovered by ASTRON astronomer Anne Archibald in 2009.
Both also exhibit powerful jets that rival those of black holes.
Further observations have been planned to uncover what makes these transitional systems different from other neutron stars.