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Radio Pulsar Emission and Crustal Field Evolution

Radio Pulsar Emission and Crustal Field Evolution. Ulrich R.M.E. Geppert DLR Bremen University of Zielona Gora. Collaboration :. J. Gil & G. Melikidze radio pulsar physics. J. Pons & D. Viganò EMHD, numerics. P artially S creened G ap M odel for Radio Pulsars.

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Radio Pulsar Emission and Crustal Field Evolution

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  1. Radio Pulsar Emission andCrustal Field Evolution Ulrich R.M.E. Geppert DLR Bremen University of Zielona Gora NS2014 Firenze

  2. Collaboration: J. Gil & G. Melikidze radiopulsarphysics J. Pons & D. Viganò EMHD, numerics NS2014 Firenze

  3. PartiallyScreenedGap Model for Radio Pulsars (seetalkof A. Szary, NS2014) Conditionsforsufficientelectronpositron pair creation: 1. surfacefieldG 2. curvatureradiusofkm NS2014 Firenze

  4. 1. surfacefieldG Medin & Lai 2007: forgapcreation G (observed) NS2014 Firenze

  5. 2. curvatureradiusofkm partofparticleenergytransferredtoradiation gapheightcm, dipolarfieldcm cm for NS2014 Firenze

  6. Can crustalfieldevolutionprovide such structures? complexmagneto-thermal processes codethatcanmodelthem: Viganò, Pons, Miralles 2012 successfullyappliedby Viganò etal. 2013 (seetalkof J. Pons) NS2014 Firenze

  7. Field evolution in thecrust: microphysics, EoSand on thermal history NS2014 Firenze

  8. mainproblem: „initial“ conditions strengthandstructureofand at the „beginning“ NS2014 Firenze

  9. fieldstructure at thebeginning: - MHD equilibrium? immediately after PNS phase? - Hall equilibrium? - onsetofcrystallization? fewhours, dayslater Ohmicdiffusion/dissipation NS2014 Firenze

  10. MHD equilibrium: toroidalcomponentofhastovanish onlywithinclosed (within thestar) fieldlinesof NS2014 Firenze

  11. MHD equilibrium in normal matter, const. density Lyutikov, 2010 confinedto a small equatorialbeltof closedpoloidalfieldlines I: poloidalcurrent F: toroidalcurrent qualitativelysimilar form forbarotropicand non-barotropicEoS (Fujisawa, Yoshida,Eriguchi, 2012), forstratifiedand SCII (Lander, Andersson, Glampedakis, 2012) NS2014 Firenze

  12. MHD equilibriumstable? Yes, twistedtorusfield(Braithwaite&Nordlund, 2004) after hours … days: crystallizationstarts at crust-core interface there: electron MHD Hall equilibrium? NS2014 Firenze

  13. Hall equilibrium: quitesimilarto MHD equilibrium Gourgouliatosetal. 2013: Can itbeestablished at all? ContinuousOhmicdecay! Drives differencebetween MHD andeMHDevolution? NS2014 Firenze

  14. Gourgouliatosetal. 2013: evenif MHD equilibrium at electronfraction NS2014 Firenze

  15. quadrupolartoroidalcomponent higherorderpoloidalandtoroidalmultipoles Hall equilibrium will bereachedonlywhen hasbeendissipatedmuch NS2014 Firenze

  16. observationalclues on internalfieldstructure: NS2014 Firenze

  17. Shabaltas & Lai 2012: lightcurveofyoung NS in Kes79 relativelyweakdipolefield best fit: strong crustaltoroidalfield NS2014 Firenze

  18. Rea etal. 2010: SGR 0418+5729 „…,a large fractionoftheradiopulsarpopulationmayhave magnetar like internalfieldsnot reflected in their normal dipolarcomponent.“ Geppert etal. 2006: pulsed thermal X-rayemission strong crustaltoroidalfields NS2014 Firenze

  19. initial fieldconfiguration: axial symmetry: vanishing in the polar region NS2014 Firenze

  20. promising model: , i.e. standardcooling at G, G impurityparameter: g g NS2014 Firenze

  21. NS2014 Firenze

  22. yr yr yr yr NS2014 Firenze

  23. decays in the South surface NS2014 Firenze

  24. However: confinded in closedlinessimilarstructures - maximumin core - at crustcoreinterface strong but noproblem NS2014 Firenze

  25. NS2014 Firenze

  26. NS2014 Firenze

  27. Conclusions: - magneticspotiscreated in yr - meridional spotscale, verycloseto North pole if crustalconfinedfield, at iffieldpenetratescore - spotismaintainedoverfewyr - reflectsthetheinfluenceofthefield on theheatflow NS2014 Firenze

  28. electric conductivity in deepcrustallayer hastobe not too large important: isnecessary, whileforsmaller large impuritycoefficient proof: same model but NS2014 Firenze

  29. NS2014 Firenze

  30. Not in contradictionto Pons, Viganò, Rea 2013: large necessarytoexplainslowspin of X-raypulsars!! NS2014 Firenze

  31. fieldstrength at thebeginning: if G : not sufficentfor creationof a magneticspotwith ||G ifG: too strong local Joule heating, too rapid fielddecay GG NS2014 Firenze

  32. fieldstructure at thebeginning: bothanddipolar canbeeitherconfinedtothecrustor threadthecorewithconfindedwithin closedpoloidalfieldlines NS2014 Firenze

  33. Requiredmagnetic „hotspots“ are created on therighttimescaleandwith sufficientstrengths, quiteindependently on the initial fieldstructurefor initial fieldstrengththataretypicalfor youngneutronstars! NS2014 Firenze

  34. Next (and urgent) task: 3D non-axialsymmetricfields!!! NS2014 Firenze

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