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Mass and Radius Constraints Using Magnetar Giant Flare Oscillations

Alex T. Deibel. Mass and Radius Constraints Using Magnetar Giant Flare Oscillations. With: Edward F. Brown (Michigan State University) Andrew W. Steiner (INT, University of Washington). HEAD Meeting 2013. Apr-8-2013. Magnetar Giant Flares - QPOs. Giant flares triggered by

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Mass and Radius Constraints Using Magnetar Giant Flare Oscillations

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  1. Alex T. Deibel Mass and Radius Constraints Using Magnetar Giant Flare Oscillations With: Edward F. Brown (Michigan State University) Andrew W. Steiner (INT, University of Washington) HEAD Meeting 2013 Apr-8-2013

  2. Magnetar Giant Flares - QPOs • Giant flares triggered by crust reconfiguration • Modeled crust oscillations can be compared to QPOs Strohmayer & Watts 2006 Figure: Robert Duncan Deibel Apr-8-2013

  3. Crust composition • Nuclei crystal lattice • Neutron-rich nuclei • Degenerate electron • and neutron gases • Magnetic field melts • the crust and changes • crust thickness Deibel, Steiner, and Brown 2013 (submitted) Deibel Apr-8-2013

  4. Bz Bz ’ = 0 Surface Outer Crust (Z, N), e Neutron Drip   Inner Crust (Z, N), e, n Core ’ = 0 Perturbing the crust Deibel Apr-8-2013

  5. Assigning crust modes to QPO frequencies Equilibrium Nuclei Solve for  Schumaker & Thorne 1983 Piro 2005 Samuelsson & Andersson 2007 Steiner & Watts 2009 = Deibel Apr-8-2013

  6. Constraining masses and radii EOS: Steiner et al. 2010 Deibel, Steiner, and Brown 2013 (submitted) Deibel Apr-8-2013

  7. Summary Choose a mass and radius from Steiner et al. EOS Find crust composition and shear modulus Integrate perturbation through the crust Compare eigenmodes to QPOs Magnetar masses and radii agree to within 1 with PREs and LMXBs from Steiner et al. 2010 Deibel Apr-8-2013

  8. Extras

  9. Discovery of Magnetars • Class of pulsars with recurring gamma ray emission (SGRs) Getting the magnetic field: • Observe a pulsar’s period and spin-down rate • Assume a moment of inertia to get a dipole magnetic field Deibel Apr-8-2013

  10. Crust Modes • QPOs are torsional modes • Oscillations confined to the crust • Crust modes will depend on • crust composition atmosphere Crust superfluid Core 1 km 10 km Deibel Apr-8-2013

  11. Magnetic Field - Landau Quantization Shell effects - Magic Numbers Dieperink 2009 Deibel Apr-8-2013

  12. Model addition (1): Shell Effects No shell effects With shell effects Deibel Apr-8-2013

  13. Model addition (2): Magnetic Field B = 0.0 G B = 2.0·1015 G Deibel Apr-8-2013

  14. Core equation of state 1.5 M 1.0 M Steiner, Lattimer, Brown 2010 Deibel Apr-8-2013

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