1、Wind braking of magnetars,H. Tong (仝号)Xinjiang Astronomical Observatory, Chinese Academy of SciencesCollaborators: 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 neutron
2、star Magnetar: a special king of pulsars (powered by magnetic energy)Anomalous X-ray pulsar (AXP)Soft gamma-ray repeater (SGR),Crab,Magnetarsmy favriate!,Timing events of magnetars,Basics: large P and Pdot Varying period derivativesLow magnetic field magnetar (small Pdot)Anti-glitchNegative correlat
3、ion between Lx and Pdot,NOT including glitches of magnetars, See Lu Jiguangs talk,Woods+ 2007,bursts,A period of enhanced spindown,Varying spindown ratePSR J1622-4950 (Levin+ 2012),Decreasing period derivative of the second low-B magnetar,Tong & Xu 2013 RAA,Scholz+ 2014,Decreasing spindown rate,Spin
4、down behavior of the Galactic center magnetar, Kaspi+ 2014,1. Decreasing Lx2. Increasing spindown ratenegative correlation betweenLx 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 many timing event
5、s 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-Eddington luminosity an
6、d 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 induced star quake mo
7、del (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 profileWhen flowing out, this particle compoent will also ta
8、ke away the rotational energy of the pulsar - spindownDiple radiation+particle component: wind braking model (Xu & Qiao 2001, for normal pulsars),Various winds,1. Solar wind2. Steller wind: Wolf-Rayet star -Ib,Ic SNe;HMXBs (wind accreting NSs)3. Wind of pulsars and magnetars,The solar wind which we
9、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,Rotational energy: magnetic dipol
10、e 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 summaryMagnetism-powered particle windWhen Lp
11、 Edot, a much lower magnetic field (plus higher order effects, magnetar case),Summary of wind braking of magnetars,1. Wind braking: Wind-aided spin down A lower surface dipole fieldMagnetars=NS+strong multipole field2. Explain challenging observations of magnetarsTheir SNe energies are of normal val
12、ueNon-detection of magnetars by Fermi-LATThe problem of low-B SGRsThe relation between magnetars and HBPSRsA decreasing Pdot during magnetar outburst3. Low luminosity mangetars more likely to have radio emissons4. Two predictionsA magentism-powered PWNA braking index n3,SGR 0418+5729: long term flux
13、 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 decresing particle wind,Spindown behavior
14、of the Galactic center magnetar, Kaspi+ 2014,1. Decreasing Lx2. Increasing spindown ratenegative correlation betweenLx and Pdot,Changes of polar cap opensing angle, Tong arXiv:1403.7898,Anti-glitch of magnetar 1E 2259+586,Archibald+ (2013), Nature,Anti-glitch,14 days interval,Modeling anti-glitch,Ly
15、utikov (arXiv:1306.2264): corona-mass-eruption-like modelTong (1306.2445): wind brakingKatz (1307.0586): retrograde accretionOuyed+ (1307.1386): retrograde accreting quark-nova remnantHuang+ (1310.3324): collision by a small body6. .,Model 1& 2 are in the magnetar domain,Anti-glitch in the wind brak
16、ing scenarioTong 2014 ApJ,Due to an enhanced particle windAnti-glitch always accompanied by radiative eventsNo anti-glitch, but a period of enhanced spindown Future anti-gltich without radiative event or a very small timescale can rule out the wind braking model,Woods+ 2007,bursts,A period of enhanc
17、ed spindown,If ,Anti-glitch: due to a stronger particle wind? ? ? ? ? ?: a weaker particle wind/the particle wind disappeared,Spindown behavior of intermittent pulsarsLi, Tong+ 2014 ApJ,Conclusions: Braking mechanism of pulsars and magnetars,Magnetic dipole braking: perpendicular rotator in vacuum;
18、must be wrong; correct to the 1st order approximation (1969); only a pedagogical model1. Wind braking of pulsars: 2nd order effect (braking index, timing variations Correlations between the timing and radiative events (low-B magnetars, anti-glitch etc),If magnetars do not exist at all .,1. NS+twiste
19、d 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,
