Simulating accreting neutron stars with dipolar and complex magnetic fields
Abstract
NASA's NICER telescope has recently provided evidence for non-dipolar magnetic field structures in rotation-powered millisecond pulsars. These stars are assumed to have gone through a prolonged accretion spin-up phase, begging the question of what accretion flows onto stars with complex magnetic fields would look like. In this talk, I will be discussing results from a suite of axisymmetric GRMHD simulations of accreting neutron stars for dipole, quadrupole, and quadrudipolar stellar field geometries. We find that the location and size of the accretion columns resulting in hotspots changes significantly depending on initial stellar field strength and geometry. The simulations inform on the variability properties of the hotspots which can aid in future pulse-profile modeling of accreting sources. We also quantify stellar torque and jet power resulting from disk magnetosphere interaction and show that the model provides a viable mechanism to explain the observed radio jet power in strong and weak stellar magnetic field cases. I will also show preliminary results from 3D GRMHD simulations of accreting neutron stars with oblique magnetospheres.
- Publication:
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44th COSPAR Scientific Assembly. Held 16-24 July
- Pub Date:
- July 2022
- Bibcode:
- 2022cosp...44.2375D