| Neutron stars and black holes are the two densest and most extreme forms of matter known in the Universe. When a neutron star or a black hole exists in a binary system with a companion star, they can accrete material and blast a small amount back out in powerful jets at relativistic speeds. Until recently, it was thought that black holes were the kings of jet formation - systems containing neutron stars were only visible when they were accreting vigorously, whereas black hole systems could be seen even when only nibbling on a trickle of material.
This simple picture has now gotten a good deal more complex, with the publication of radio observations of PSR J1023+0038, one of the so-called "transitional millisecond pulsars", made with the Very Large Array and the European VLBI Network. The image shows an artist's conception of the PSR J1023+0028 system. The radio observations, which trace the strength of the jet, show that these particular neutron star systems make strong jets even though they are only accreting a small amount of material. It seems likely that a special combination of the neutron star spin period and magnetic field strength may be required to supercharge the system's jet, which also leads to strong production on gamma-rays. Further observations of other, newly discovered transitional millisecond pulsars are planned to further investigate what makes these systems punch above their weight in jet formation.
The research was led by ASTRON scientist Adam Deller and included other ASTRON and JIVE scientists Javier Moldon, Jason Hessels, Anne Archibald, Zsolt Paragi, George Heald and Nicolas Vilchez. It was published this week in the Astrophysical Journal (ApJ, volume 809, issue 1: arXiv http://arxiv.org/abs/1412.5155 ).