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

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

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

Deibel Apr BzBz BzBz Surface Core Neutron Drip Outer Crust (Z, N), e Inner Crust (Z, N), e, n    ’ = 0 Perturbing the crust

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

Constraining masses and radii Deibel Apr EOS: Steiner et al Deibel, Steiner, and Brown 2013 (submitted)

Summary Choose a mass and radius from Steiner et al. EOS 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 Deibel Apr Find crust composition and shear modulus

Extras

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

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

Shell effects Deibel Apr Magnetic Field - Landau Quantization - Magic Numbers Dieperink 2009

With shell effectsNo shell effects Deibel Apr Model addition (1): Shell Effects

B = 0.0 GB = 2.0·10 15 G Deibel Apr Model addition (2): Magnetic Field

Core equation of state Deibel Apr Steiner, Lattimer, Brown M  1.0 M 