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Ferromagnetism in nuclear matter (and how it relates to neutron stars)

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. Neutron stars/Pulsars. Remnant core of massive star that explode in a core-collapse supernova

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Ferromagnetism in nuclear matter (and how it relates to neutron stars)

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  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 • Ires dependent on equation of state of interior Link et al, PRL 83 (17) 1999

  5. Magnetars • Pulsars with super-strong magnetic fields (SGR, AXP) • ~1015 Gauss magnetic field (normally 1012 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

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