1. Ferromagnetism in nuclear matter (and how it relates to neutron stars) Jacobus Diener (PhD student) Supervisors: Prof FG Scholtz and Prof HB Geyer Department of Physics Stellenbosch University

2. Neutron stars/Pulsars Remnant core of massive star that explode in a core-collapse supernova  One of the most dense states of matter Crab Nebula HST image from http://chandra.harvard.edu/

3. Neutron stars/Pulsars Commonly observed as pulsars  Rapidly rotating neutron star with radio-emissions at magnetic poles  Glitches: Sudden spin-up in rotation frequency  Magnetars: Pulsars with super-strong magnetic field www.astrocu.unam.mx/neutrones/dany.html

4. Glitches Sudden spin-ups in period of pulsar  Crust and interior are differentially rotating  Neutron superfluid  Spin-ups relating to decoupling of vortices at crustal boundary “A” parameter from observational data, available from HartRAO I res dependent on equation of state of interior Link et al, PRL 83 (17) 1999

5. Magnetars Pulsars with super-strong magnetic fields (SGR, AXP)  ~10 15 Gauss magnetic field (normally 10 12 Gauss)  Dynamo action  Ferromagnetic phase Ferromagnetism: Alignment of intrinsic spins of particles in pulsar interior  Relativistic description of ferromagnetism

6. Ferromagnetism Spontaneous alignment of spin to minimize the energy of the system  Transition density Need to know matter present as well as equation of state of interior of pulsar (magnetar) http://www.tf.uni-kiel.de/matwis/

7. F. Weber, Prog. Part. Nucl. Phys. 54 (2005)

8. Model for pulsar matter Relativistic, effective field theory  Meson mediate interaction between nucleons  Describe ferromagnetism in this setting  Equation of state General Relativity to model rapidly rotating ultra- dense fluid Observational data  HartRAO

9. Constraining equation of state

10. Conclusion Pulsars are extra-terrestrial laboratories for nuclear physicists  Test descriptions of nuclear matter Provides theoretical interpretation for pulsar observations Need for observers and theorist to work together

11. Word of thanks SA SKA project and Stellenbosch University for supporting this research Kim and Annah who deals with all the bursary admin