Ferromagnetism in nuclear matter (and how it relates to neutron stars)
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Transcript of 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 PhysicsStellenbosch University
Neutron stars/Pulsars• Remnant core of massive star that explode
in a core-collapse supernovaOne of the most dense states of matter
Crab NebulaHST image from http://chandra.harvard.edu/
Neutron stars/Pulsars• Commonly
observed as pulsarsRapidly 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
Glitches• Sudden spin-ups in period of pulsar
Crust and interior are differentially rotating Neutron superfluidSpin-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
Ares
crust
I
I
Link et al, PRL 83 (17) 1999
Magnetars
• Pulsars with super-strong magnetic fields (SGR, AXP)~1015 Gauss magnetic field (normally 1012
Gauss)Dynamo actionFerromagnetic phase
• Ferromagnetism: Alignment of intrinsic spins of particles in pulsar interiorRelativistic description of ferromagnetism
Ferromagnetism
• Spontaneous alignment of spin to minimize the energy of the systemTransition density
• Need to know matter present as well as equation of state of interior of pulsar (magnetar)
http://www.tf.uni-kiel.de/matwis/
F. Weber, Prog. Part. Nucl. Phys. 54 (2005)
Model for pulsar matter• Relativistic, effective field theory
Meson mediate interaction between nucleons
Describe ferromagnetism in this settingEquation of state
• General Relativity to model rapidly rotating ultra-dense fluid
• Observational dataHartRAO
Constraining equation of state
Conclusion• Pulsars are extra-terrestrial laboratories
for nuclear physicistsTest descriptions of nuclear matter
• Provides theoretical interpretation for pulsar observations
• Need for observers and theorist to work together
Word of thanks
• SA SKA project and Stellenbosch University for supporting this research
• Kim and Annah who deals with all the bursary admin