Multiband observation and theory of magnetars H. Tong ( 仝号 ) Xinjiang Astronomical Observatory, CAS For 2013 Pulsar summer

Contents Introduction Radio observations of magnetars Soft X-ray observations of magnetars Optical/IR/HX/gamma observations Magnetar/PWN/SNR system Summary

Where are they?

What's AXPs & SGRs AXPs: anomalous X-ray pulsars Lx>Edot (not necessary!) No binary signature SGRs: soft gamma-ray repeaters Soft: typical photon energy is lower Repeater: recurrent bursts The same class!

Critical magnetic field Cyclotron energy = electron rest mass Microscopic process: QED

Traditional magnetar model (2008) Magnetar = 1.young NS (SNR & MSC) 2.B_dip> B _ QED = 4.4*10^13 G (braking) 3.B_mul=10^14-10^15 G (burst and super-Eddington luminosity and persistent emission)

prehistory of magnetars 1932: Chadwick, discovery of neuton 1932: Landau, celestial objects with nuclear density 1934: Baade & Zwicky, NSs born in SNe 1939: Oppenheimer & Volkoff, NS structure M_sun, 10 km 1967: Hewish & Bell, discovery of (rotation- powered) pulsars 1971: Giacconi et al., discovery of accretion- powered X-ray pulsars

A brief history of magnetars 1979: giant flare of SGR : anomalous X-ray pulsars 1992: “magnetars” 1998: Timing of SGR giant flare of SGR : multiwave era (radio, IR, HX) 2010: “low magnetic field” magnetar (B<7.5*10^12 G)

The magnetar model 1. Duncan & Thompson 1992: 1.Dynamo 2.spin-down 2. Usov 1992: millisecond magnetar as central engine for GRBs 3. Paczynski 1992: super-Eddington luminosity 1992: “magnetar”

Magnetar timing Kouveliotou et al. (1998) SGR : P=7.47s Pdot= 8.24*10^-11 tau=1500 yr B=8*10^14. G (assuming magnetic dipole braking!)

Giant flare (Hurley et al. 1999) 1998: SGR Modeling: Yu+ 2013

Other observations Burst from one AXP 1E (2002) Glitches during outburst of 1E (2003) Intermediate flare from 1E (2009) AXPs & SGRs belong to the same class!

Observations for the magnetar model (Tong & Xu 2011) 1. B from P and Pdot 2. Cyclotron lines (?) 3. Pulsating tail 4. Super-Eddington luminosity 5. SGR-like bursts from HBPSR 6....(other more model dependent ones)

Failed predictions 1. SNe more energetic (2006) 2. A larger kick velocity (2007) 3. No radio emissions (2006) 4. High-energy gamma-ray detectable by Fermi/LAT (2010) 5. B>B QED (2010) 6. Always a large L x (L x >E dot ): transients & HBPSRs 7.Precession

3+1 things to do 1.Origin of strong-B 2.Emission mechanisms in the magnetar domain 3.Alternative models of AXPs/SGRs 4.Relation between magnetars and other pulsar-like objects (XDINSs, CCOs, HBPSRs, and normal pulsars)

Various alternatives 1. NS+twisted magnetosphere (Thompson et al. 2002; Beloborodov+ 2007, 2009) 2. Wind braking of magnetars (Tong et al. 2013) 3. Fallback disk model (Alpar 2001) 4. Accretion induced star quake model (Xu et al. 2006) 5. Quark nova remnant (Ouyed et al. 2007) 6. Accreting WD model (Malheiro et al. 2011)

No radio emissions from magnetars? No radio emissions from magnetars (QED calculations, Baring & Harding 1998) Transient pulsed radio emssions from AXP XTE J (Camilo et al. 2006) Peculiarities (Mereghetti 2008) : variable flux and pulse profile Flat spectra Transient in nature

Levin et al. 2010

Levin et al. 2012

“Fundamental plane” of magnetar radio emissions (Rea et al. 2012)

“Fundamental plane” of magnetar radio emissions (Rea+ 2012) A magnetar is radio-loud if and only if: Rotation-powered

Failed predictions Failed in one new source Swift J (Tong, Yuan & Liu 2013, RAA, 13, 835; obs /6) GBT nondetection (Esposito+ arXiv: ; obs ) GMRT nondetection (obs: )

Alternative idea of magnetar radio emissions “Low luminosity magnetars are more likely to have radio emissions” magnetism-powered

Interesting application VLBI measurement of magnetar kick velocity: Failed predictions XTE J : Helfand E : Deller J : ?

4 th radio-loud magnetar at the Galatic Center: Rea et al. 2013

Espinoza et al. 2011: From normal pulsars to magnetars? Relations with radio pulsars Modeling: Liu+ 2012

Soft X-ray observations Timing P & Pdot measurement (1998) Glitch (2000) Low-B magnetars (2010) Anti-glitch (2013) Outbursts, transient Relations with other pulsar-like objects (XDINSs, CCOs etc)

Magnetar timing Kouveliotou et al. (1998) SGR : P=7.47s Pdot= 8.24*10^-11 tau=1500 yr B=8*10^14. G (assuming magnetic dipole braking!) Problems: 1. the existence of HBPSRs, 2. the Pdot variations of magnetars, 3. Low-B magnetars (2010)!

Glitches in magnetars Glitch in AXP 1E (Kaspi+ 2003) 1.Large amplitude: 2.Accompanied by outburst 3.Increase in spindown rate: 2 times larger

Outburst of 1E Kaspi et al. (2003)

Summary of glitches in magnetars (Dib+ 2008) 1.Most AXPs show glitches 2.Some (and only some) are associated with radiative events 3.Large recoveries (Q>1): superfluid of magnetars rotates slower than the crust?

Low-B magnears: two sources ( ) 1. SGR (Rea+2010) 2. Swift J (Rea+2012)

SGR Bursts detected by Fermi-GBM, 2009/6/5 (van der Horst et al. 2010) Early X-ray and optical obs: Pdot<1.1*10^-13 B dip <3*10^13 G (Esposito et al. 2010) One year obs: Pdot<6.0*10^-15 (P=9.1sec) B dip <7.5*10^12 G (Rea et al. 2010, Science)

Implications Assuming magnetic dipole braking: B dip <7.5*10^12 G tau_c>2.4*10^7 yr Rotational energy: E dot <3.1*10^29 erg s^-1 X-ray luminosity: Lx=6.2*10^31 erg s^-1

Implications-II Assuming B-powered: B mul >5*10^14 G

Problems? Magnetar = young NS (SNR etc) B dip > 4.4*E13 G (braking) B mul =10^14-10^15 G (burst and persistent emission and super-Eddington luminosity)

“Old magnetars” Turolla et al. (2011) Magnetars: strong internal toroidal field

Alternatives Old magnetars (Turolla+2011) Wind braking (Tong& Xu 2013) Disk spindown (Alpar+2011) Quark-Nova remnant (Ouyed+2011) White dwarf model (Malheiro+2012)

Wind braking of magnetars Tong+2013, ApJ

Wind braking of SGR Tong & Xu 2012, ApJL

Anti-glitch of magnetar 1E ● Archibald+ (2013), Nature

Anti-glitch in SGR ● Woods+ (1999)

Net spindown of PSR J ● Livingstone+ (2010) Q=8.7

Modeling anti-glitch 1.Lyutikov (arXiv: ): corona-mass- eruption-like model 2.Tong (arXiv: ): wind braking 3.Katz (arXiv: ): retrograde accretion 4.Ouyed+ (arXiv: ): retrograde accreting quark-nova

Wind braking Particle wind luminosity:

Anti-glitch in the wind braking scenario 1.Due to an enhanced particle wind 2.Anti-glitch always accompanied by radiative events 3.No anti-glitch, but an enhanced period of spindown ● Future anti-gltich without radiative event or a very small timescale can rule out the wind braking model

Other observations A debris disk around one AXP (Wang et al. 2006) QPOs (Israel et al. 2005): magnetar seismology “free oscillation of the central star”

Summary: multiband observations transient radio emissions Soft X-ray activities (timing, radiative) Optical/IR: fallback disk (Wang+ 2006) Hard X-ray: burst (& giant flares) & persistent Gamm-ray: nondetection by Fermi (Failed predictions) PWN/SNR: normal SNe energies (failed predictions) & possible PWN

Summary: Magnetars in astrophysics (Kaspi 2010) 1.AXP/SGR 2.XDINSs: dead magnetar 3.CCO: magnetar-in-waiting /disk braked down magnetar 4.HBPSR: magnetar activities also seen (PSR J ) 5.Low B SGR: magnetar activities in normal pulsars in the future! 6.Magnetars in binary system?

Thanks!

Failed predictions I: SNe energy Vink & Kuiper (2006)

Possible solution Spin-down time scale: Wind braking of magnetars (Tong+ 2012) : a dipole field 10 times lower A high dipole field, magnetic dipole braking

Failed predictions II: kick velocity Helfand et al. (2007) (VLBA)

VLBI obs of the second radio-loud magnetar: AXP 1E Deller et al. 2012

Proper motion of SGR and SGR through NIR astrometry (arXiv: )

Failed predictions III: No radio emissions No radio emissions from magnetars (QED calculations, Baring & Harding 1998) Transient pulsed radio emssions from AXP XTE J (Camilo et al. 2006) Peculiarities (Mereghetti 2008) : variable flux and pulse profile Flat spectra Transient in nature

“Fundamental plane” of magnetar radio emissions (Rea et al. 2012)

“Fundamental plane” of magnetar radio emissions A magnetar is radio-loud if and only if: Failed in one new source (Tong, Yuan & Liu 2013) “Low luminosity magnetars are more likely to have radio emissions”

Failed prediction IV: Fermi/LAT obs of 4U (Sasmaz Mus & Gogus 2010; Tong, Song, & Xu 2010) Exposure: 31.7 Ms No detection!

Fermi/LAT observation of all magnetars (Fermi-LAT collaboration 2010; Tong, Song, & Xu 2011)

Possible solutions 1. Accretion model for AXPs and SGRs 2. Wind braking of magnetars: a different magnetospheric structure

Failed predictions V: Low-B SGR (Rea et al. 2010)

Problems of SGR B_mul>>B_dip? 2. Burst-active at 10^6-10^7 yr? Too many SGR in our Galaxy (Muno et al. 2008) 3. What about XDINSs?

Another possibility (Tong & Xu 2012) A normal magnetar Instead of a low-B magnetar

Failed predictions VI: A radio loud magnetar (Levin et al. 2010) PSR J Discovered 2009/04 HRTU survey, Parkes Edot=8.5*10^33 erg s^-1 Lx=2.5*10^33 erg s^-1 (Chandra)

P-Pdot diagram

Why Lx so low? Also transient magnetars, e.g., XTE J and HBPSRs Corona model is not the full story!

Failed predictions: VII free precession of magnetars Prolate in shape Free precession (Thompson et al. 2000) :