1、Wind braking of magnetars,H. Tong (仝号) Xinjiang Astronomical Observatory, Chinese Academy of Sciences Collaborators: J.P. Yuan (XAO), R.X. Xu (PKU), W. Wang (NAOC) 2014.10,For QCS 2014PKU,Homepage: star, pulsar and magnetar,Neutron star=a star made of neutrons (NO!) Pulsar=rotating magnetized neutr
2、on star Magnetar: a special king of pulsars (powered by magnetic energy) Anomalous X-ray pulsar (AXP) Soft gamma-ray repeater (SGR),Crab,Magnetars my favriate!,Timing events of magnetars,Basics: large P and Pdot Varying period derivatives Low magnetic field magnetar (small Pdot) Anti-glitch Negative
3、 correlation between Lx and Pdot,NOT including glitches of magnetars, See Lu Jiguangs talk,Woods+ 2007,bursts,A period of enhanced spindown,Varying spindown rate PSR J1622-4950 (Levin+ 2012),Decreasing period derivative of the second low-B magnetar,Tong & Xu 2013 RAA,Scholz+ 2014,Decreasing spindown
4、 rate,Spindown behavior of the Galactic center magnetar, Kaspi+ 2014,1. Decreasing Lx 2. Increasing spindown rate negative correlation between Lx and Pdot,Anti-glitch of magnetar 1E 2259+586,Archibald+ (2013), Nature,Anti-glitch,14 days interval,Open questions,How magnetars are spun down? Why so man
5、y timing events in and only in magnetars? Unified spindown mechanism of pulsars and magnetars,My answer: wind braking (Tong et al. 2013, ApJ, 768, 144),Traditional magnetar model (Mereghetti 2008),Magnetar = young NS (SNR & MSC) Bdip BQED=4.41013 G (braking) Bmul=1014 -1015 G (burst and super-Edding
6、ton luminosity and persistent emission),Various alternatives (Tong & Xu 2014),1. NS+twisted magnetosphere (Thompson et al. 2002; Beloborodov 2009) 2. Wind braking of magnetars (Tong et al. 2013) 3. Coupled magnetic and thermal evolution (Vigano+2013) 4. Fallback disk model (Alpar 2001) 5. Accretion
7、induced star quake model (Xu et al. 2006) 6. Quark nova remnant (Ouyed et al. 2007) 7. Accreting WD model (Paczynski 1990),General pictures of wind braking,Pulsars have a magnetosphere, where there is particle acceleration and subseuqent radiation process pulse profile When flowing out, this particl
8、e compoent will also take away the rotational energy of the pulsar spindown Diple radiation+particle component: wind braking model (Xu & Qiao 2001, for normal pulsars),Various winds,1. Solar wind 2. Steller wind: Wolf-Rayet star Ib,Ic SNe; HMXBs (wind accreting NSs) 3. Wind of pulsars and magnetars,
9、The solar wind which we can feel its existence,Magnetic dipole braking of pulsars,Rotating (perpendicular) dipole in vaccum! Only as first order approximation to the real case (Goldreich & Julian 1969, Ruderman & Sutherland 1975) It is only a pedagogical model!,wind braking of normal pulsars,Rotatio
10、nal energy: magnetic dipole radiation+particle wind (rotation-powered) Effects: higher order modifications, e.g. braking index (Xu Li, Tong+ 2014 ),Typical pulsar-SNR system (Gaensler & Slane 2006),Intermittent pulsars B1931+24 (Kramer+ 2006),Wind braking of magnetars (Tong+ 2013),In summary Magneti
11、sm-powered particle wind When Lp Edot, a much lower magnetic field (plus higher order effects, magnetar case),Summary of wind braking of magnetars,1. Wind braking: Wind-aided spin downA lower surface dipole field Magnetars=NS+strong multipole field 2. Explain challenging observations of magnetars Th
12、eir 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 3. Low luminosity mangetars more likely to have radio emissons 4. Two predictions A magentism-powered PWN A brak
13、ing index n3,SGR 0418+5729: long term flux evolution (Rea+ 2013),Tong & Xu 2012 ApJ,Low B magnetar due to a small inclination angle,Swift J1822.3-1606: long term flux evolution (Scholz+ 2014),Decreasing period derivative of the second low-B magnetar,Tong & Xu 2013 RAA,Scholz+ 2014,Decreasing Pdot a
14、decresing particle wind,Spindown behavior of the Galactic center magnetar, Kaspi+ 2014,1. Decreasing Lx 2. Increasing spindown rate negative correlation between Lx and Pdot,Changes of polar cap opensing angle, Tong arXiv:1403.7898,Anti-glitch of magnetar 1E 2259+586,Archibald+ (2013), Nature,Anti-gl
15、itch,14 days interval,Modeling anti-glitch,Lyutikov (arXiv:1306.2264): corona-mass-eruption-like model Tong (1306.2445): wind braking Katz (1307.0586): retrograde accretion Ouyed+ (1307.1386): retrograde accreting quark-nova remnant Huang+ (1310.3324): collision by a small body 6. .,Model 1& 2 are i
16、n the magnetar domain,Anti-glitch in the wind braking scenario Tong 2014 ApJ,Due to an enhanced particle wind Anti-glitch always accompanied by radiative events No anti-glitch, but a period of enhanced spindownFuture anti-gltich without radiative event or a very small timescale can rule out the wind
17、 braking model,Woods+ 2007,bursts,A period of enhanced spindown,If ,Anti-glitch: due to a stronger particle wind ? ? ? ? ? ?: a weaker particle wind/the particle wind disappeared,Spindown behavior of intermittent pulsars Li, Tong+ 2014 ApJ,Conclusions: Braking mechanism of pulsars and magnetars,Magn
18、etic dipole braking: perpendicular rotator in vacuum; must be wrong; correct to the 1st order approximation (1969); only a pedagogical model 1. Wind braking of pulsars: 2nd order effect (braking index, timing variations Correlations between the timing and radiative events (low-B magnetars, anti-glit
19、ch etc),If magnetars do not exist at all .,1. NS+twisted magnetosphere (Thompson et al. 2002; Beloborodov 2009) 2. Wind braking of magnetars (Tong et al. 2013) 3. Coupled magnetic and thermal evolution (Vigano+2013) 4. Fallback disk model (Alpar 2001) 5. Accretion induced star quake model (Xu et al. 2006) 6. Quark nova remnant (Ouyed et al. 2007) 7. Accreting WD model (Paczynski 1990) AXPs and SGRs must be quark star+fallback disk systems (Tong & Xu 2011,arXiv:1110.1975),See R. X. Xus talk,
