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1、Magnetars: wind brakingH. TongXinjiang Astronomical Observatory PAC2012, XiangshanWhere are they?2Traditional magnetar model Magnetar = 1.young NS (SNR & MSC)2.Bdip BQED=4.41013 G (braking)3.Bmul=1014 -1015 G (burst and super-Eddington luminosity and persistent emission)3“Magnetic dipole braking” of
2、 normal pulsarsRotational energymagnetic dipole radiation+particle wind (rotation-powered)Effects: higher order modifications, e.g. braking index (Michel 1969; Manchester 1985; Xu & Qiao 2001; Contopoulos & Spitkovsky 2006; Wang+ 2012)timing noise (Lyne+ 2010; Liu+ 2011)+a rotation-powered PWNExist:
3、 intermittent pulsars (Kramer+ 2006; Camilo+ 2012)Intermittent pulsars B1931+24(Kramer+ 2006)5Magnetic dipole braking is only a pedagogical model!Rotating dipole in vaccum!Only as first order approximation to the real caseNormal pulsars braked down by a rotation-powered particle windExistence of a p
4、article wind in magnetars1.Varying period derivative2.Higher level of timing noise (compared with HBPSRs)3.Magnetism-powered PWNa)Correlation between Lpwn and Lxb)Higher Lpwn/Edot7PSR J1622-4950(Levin+ 2012)8Rotational energy loss rateIn summaryMagnetism-powered particle windWhen Lp Edot, a much low
5、er magnetic field (plus higher order effects, magnetar case)9Dipole magnetic field (1): magnetic dipole brakingPolar magnetic field10Dipole magnetic field (2): wind brakingDipole magnetic field in the case of wind braking11Dipole B (case I)12Conclusions (1)1.Wind braking: Wind-aided spin downA lower
6、 surface dipole fieldMagnetars=NS+strong multipole field2.Explain challenging observations of magnetarsa)Their SNe energies are of normal valueb)Non-detection of magnetars by Fermi-LATc)The problem of low-B SGRsd)The relation between magnetars and HBPSRse)A decreasing Pdot during magnetar outburst3.
7、Low luminosity mangetars more likely to have radio emissons4.Two predictionsA magentism-powered PWNA braking index n higher B(Tong & Xu 2012)1415A paradigm shift in the future?FAST: more radio-loud magnetars, HBPSRs, intermittent pulsars “Pulsars are electromagnetic braking”Pulsars are wind brakingFor short
