Radio Pulsar Emission and Crustal Field Evolution

Radio Pulsar Emission and Crustal Field EvolutionUlrich R.M.E. GeppertDLR BremenUniversity of Zielona Gora27.03.2014NS2014 Firenze127.03.2014NS2014 Firenze2Collaboration:J. Gil & G. Melikidze

radio pulsar physicsJ. Pons & D. Vigan

EMHD, numerics27.03.2014NS2014 Firenze3Partially Screened Gap Model for Radio Pulsars(see talk of A. Szary, NS2014)Conditions for sufficient electron positron pair creation:27.03.2014NS2014 Firenze4

(observed) 27.03.2014NS2014 Firenze5part of particle energy transferred to radiation27.03.2014NS2014 Firenze6Can crustal field evolution provide such structures?complex magneto-thermal processescode that can model them: Vigan, Pons, Miralles 2012successfully applied by Vigan etal. 2013(see talk of J. Pons)27.03.2014NS2014 Firenze7Field evolution in the crust: microphysics, EoS and on thermal history27.03.2014NS2014 Firenze8main problem: initial conditions27.03.2014NS2014 Firenze9field structure at the beginning:- MHD equilibrium?- Hall equilibrium?- onset of crystallization?immediatelyafter PNS phase?few hours, days laterOhmic diffusion/dissipation27.03.2014NS2014 Firenze10MHD equilibrium:27.03.2014NS2014 Firenze11

Lyutikov, 2010I: poloidal currentF: toroidal currentMHD equilibrium innormal matter, const.densityqualitatively similar formfor barotropic and non-barotropicEoS(Fujisawa, Yoshida,Eriguchi, 2012),for stratified and SCII(Lander, Andersson, Glampedakis, 2012)1127.03.2014NS2014 Firenze12MHD equilibrium stable?Yes, twisted torus field (Braithwaite&Nordlund, 2004)after hours days: crystallization starts at crust-core interface there: electron MHDHall equilibrium?

27.03.2014NS2014 Firenze13Hall equilibrium:quite similar to MHD equilibriumCan it be established at all?Gourgouliatos etal. 2013:

Continuous Ohmic decay!Drives difference between MHD and eMHD evolution?27.03.2014NS2014 Firenze14Gourgouliatos etal. 2013:

27.03.2014NS2014 Firenze15quadrupolar toroidal componenthigher order poloidal and toroidal multipoles27.03.2014NS2014 Firenze16observational clues on internal field structure:27.03.2014NS2014 Firenze17 relatively weak dipole fieldstrong crustal toroidal field

Shabaltas & Lai 2012: lightcurve of young NS in Kes7927.03.2014NS2014 Firenze18Rea etal. 2010: SGR 0418+5729,a large fraction of the radio pulsar population may havemagnetar like internal fields not reflected in their normaldipolar component.

Geppert etal. 2006: pulsed thermal X-ray emissionstrong crustal toroidal fields27.03.2014NS2014 Firenze19

initial field configuration:27.03.2014NS2014 Firenze20promising model:27.03.2014NS2014 Firenze21

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27.03.2014NS2014 Firenze24However:27.03.2014NS2014 Firenze25

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27.03.2014NS2014 Firenze27Conclusions:27.03.2014NS2014 Firenze28large impurity coefficient27.03.2014NS2014 Firenze29

27.03.2014NS2014 Firenze3027.03.2014NS2014 Firenze31field strength at the beginning:27.03.2014NS2014 Firenze32field structure at the beginning:27.03.2014NS2014 Firenze33Required magnetic hot spots are created on the right timescale and with sufficient strengths, quite independently on the initial field structure for initialfield strength that are typical for young neutron stars!27.03.2014NS2014 Firenze34Next (and urgent) task:3D non-axialsymmetric fields!!!