1. Magnetars: wind braking
PAC2012, Xiangshan
Magnetars: wind braking
H. Tong
Xinjiang Astronomical Observatory

2. Where are they?

3. Traditional magnetar model
young NS (SNR & MSC)
Bdip> BQED=4.4×1013 G (braking)
Bmul= G (burst and super- Eddington luminosity and persistent emission) 3

4. “Magnetic dipole braking” of normal pulsars
Rotational energymagnetic 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 ) timing noise (Lyne+ 2010; Liu+ 2011) +a rotation-powered PWN
Exist: intermittent pulsars (Kramer+ 2006; Camilo+ 2012)

5. Intermittent pulsars B1931+24
(Kramer+ 2006)

6. Magnetic dipole braking is only a pedagogical model!
Rotating dipole in vaccum!
Only as first order approximation to the real case
Normal pulsars braked down by a rotation- powered particle wind

7. Existence of a particle wind in magnetars
Varying period derivative
Higher level of timing noise (compared with HBPSRs)
Magnetism-powered PWN
Correlation between Lpwn and Lx
Higher Lpwn/Edot

8. PSR J
(Levin+ 2012)

9. Rotational energy loss rate
In summary
Magnetism-powered particle wind
When Lp >> Edot, a much lower magnetic field (plus higher order effects, magnetar case)

10. Dipole magnetic field (1): magnetic dipole braking
Polar magnetic field

11. Dipole magnetic field (2): wind braking
Dipole magnetic field in the case of wind braking

12. Dipole B (case I)

13. Conclusions (1) Wind braking:
Wind-aided spin down
A lower surface dipole field
Magnetars=NS+strong multipole field
Explain challenging observations of magnetars
Their SNe energies are of normal value
Non-detection of magnetars by Fermi-LAT
The problem of low-B SGRs
The relation between magnetars and HBPSRs
A decreasing Pdot during magnetar outburst
Low luminosity mangetars more likely to have radio emissons
Two predictions
A magentism-powered PWN
A braking index n<3

14. Conclusions (2): subsequent developments
Magnetism-powered pulsar wind nebula around SGR Swift J (Younes et al. 2012)
Geometrical effect during wind braking: small inclination angle--> higher B (Tong & Xu 2012)

16. A paradigm shift in the future?
FAST: more radio-loud magnetars, HBPSRs, intermittent pulsars …
“Pulsars are electromagnetic braking”
For short
Pulsars are wind braking