Scientists have for the first time succeeded in determining the topography of both magnetic poles of a neutron star. This turned out to be possible thanks to Einstein's general theory of relativity. Neutron stars are one of the most exotic objects in the universe. They have the strongest gravitational and magnetic fields in the visible universe. The results will be announced in the journal Science on 6 September 2019.
“This neutron star, named PSR J1906 + 0746, revolves around a different heavy neutron star in a double star system. The enormous gravity that this twin star exerts on each other, curves spacetime. Therefore, the visible neutron star tilts slowly and we have managed for the first time to create a map of the two poles of such a star, "says Dr. Joeri van Leeuwen of the Netherlands Institute for Radio Astronomy ASTRON, who discovered the star in 2005.
The research team, led by Gregory Desvignes of the Max Planck Institute for Radio Astronomy in Bonn (Germany), has closely followed the tilting of the neutron star with the Arecibo and Nancay radio telescopes. From these observations, the team was able to create a map that indicates which polar regions emit radio waves, and which magnetic fields are located there.
"PSR J1906 + 0746 is a unique laboratory to investigate how neutron stars can make such bright radio radiation, and to immediately test Einstein's general theory of relativity, " says Dr. Desvignes. "As it turned out, one pole was not round, as expected, but elongated."
The result is the most precise observation of this so-called geodetic precession for heavy, compact systems. The polar maps are also important information to predict how many gravitational waves merging neutron double stars can make.
"The investigation took a long time but we have learned a lot, " says co-author Michael Kramer, also from MPIfR. Van Leeuwen adds: “We now also know that due to the tilt from 2028 on there will no longer be any radio radiation towards Earth. This neutron star will then disappear from our sight. We are lucky that we have found him. "
PSR J1906 + 0746: By tilting the axis of rotation of the pulsar a detailed map of both poles can be made ( Credit: Gregory Desvignes & Michael Kramer, MPIfR ) .
Gregory Desvignes et al .: Radio emission from a pulsar's magnetic pole revealed by general relativity, in: Science, 6 September 2019: https://science.sciencemag.org/content/365/6457/10