mass and radius constraints using magnetar giant flare oscillations
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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)
QuickTime™ and a decompressor
are needed to see this picture.
HEAD Meeting 2013 Apr-8-2013
QuickTime™ and a decompressor
are needed to see this picture.
• Giant flares triggered by
crust reconfiguration
• Modeled crust oscillations
can be compared to
QPOs
Strohmayer & Watts 2006 Figure: Robert Duncan
Deibel Apr-8-2013
Magnetar Giant Flares - QPOs
Deibel, Steiner, and Brown 2013 (submitted) Deibel Apr-8-2013
• Nuclei crystal lattice
• Neutron-rich nuclei
• Degenerate electron and neutron gases
• Magnetic field melts the crust and changes crust thickness
Crust composition
Deibel Apr-8-2013
BzBzSurface
Core
Neutron Drip
Outer Crust (Z, N), e
Inner Crust (Z, N), e, n
’ = 0
’ = 0
Perturbing the crust
Equilibrium Nuclei
Deibel Apr-8-2013
Solve for
=
Schumaker & Thorne 1983Piro 2005Samuelsson & Andersson 2007Steiner & Watts 2009
Assigning crust modes to QPO frequencies
Constraining masses and radii
Deibel Apr-8-2013EOS: Steiner et al. 2010Deibel, 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 1with PREs and LMXBs from Steiner et al. 2010
Deibel Apr-8-2013
Find crust composition and shear modulus
Extras
Discovery of Magnetars
• Class of pulsars with recurringgamma ray emission (SGRs)
Getting the magnetic field:• Observe a pulsar’s period and
spin-down rate
• Assume a moment of inertiato get a dipole magnetic field
Deibel Apr-8-2013
10 km 1 km
Core
Crustsuperfluidatm
osphere
Deibel Apr-8-2013
• QPOs are torsional modes
• Oscillations confined to the crust
• Crust modes will depend on crust composition
Crust Modes
Shell effects
Deibel Apr-8-2013
Magnetic Field- Landau Quantization
- Magic Numbers
Dieperink 2009
With shell effectsNo shell effects
Deibel Apr-8-2013
Model addition (1): Shell Effects
B = 0.0 G B = 2.0·1015 G
Deibel Apr-8-2013
Model addition (2): Magnetic Field
Core equation of state
Deibel Apr-8-2013Steiner, Lattimer, Brown 2010
1.5 M
1.0 M