Multiband observation and theory of magnetars - PowerPoint PPT Presentation

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Multiband observation and theory of magnetars

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  1. For 2013 Pulsar summer school @Beijing Multiband observation and theory of magnetars H. Tong (仝号) Xinjiang Astronomical Observatory, CAS 2013.8

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

  3. Where are they?

  4. 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!

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

  6. Traditional magnetar model(2008) • Magnetar = • young NS (SNR & MSC) • B_dip> B_QED=4.4*10^13 G (braking) • B_mul=10^14-10^15 G (burst and super-Eddington luminosity and persistent emission)

  7. 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

  8. A brief history of magnetars • 1979: giant flare of SGR 0526-66 • 1981: anomalous X-ray pulsars • 1992: “magnetars” • 1998: Timingof SGR 1806-20giant flare of SGR 1900+14 • 2006-: multiwave era (radio, IR, HX) • 2010: “low magnetic field” magnetar(B<7.5*10^12 G)

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

  10. Magnetar timing Kouveliotou et al. (1998) SGR 1806-20: P=7.47s Pdot= 8.24*10^-11 tau=1500 yr B=8*10^14. G (assuming magnetic dipole braking!)

  11. Giant flare (Hurley et al. 1999) 1998: SGR 1900+14 Modeling: Yu+ 2013

  12. Other observations Burst from one AXP 1E 1048.1-5937 (2002) Glitches during outburst of 1E 2259+586 (2003) Intermediate flare from 1E 1547.0-5408 (2009) AXPs & SGRs belong to the same class!

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

  14. Failed predictions SNe more energetic (2006) A larger kick velocity (2007) No radio emissions (2006) High-energy gamma-ray detectable by Fermi/LAT (2010) B>BQED (2010) Always a large Lx(Lx>Edot): transients & HBPSRs Precession

  15. 3+1 things to do • Origin of strong-B • Emission mechanisms in the magnetar domain • Alternative models of AXPs/SGRs • Relation between magnetars and other pulsar-like objects (XDINSs, CCOs, HBPSRs, and normal pulsars)

  16. 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)

  17. No radio emissions from magnetars? No radio emissions from magnetars (QED calculations, Baring & Harding 1998) Transient pulsed radio emssions from AXP XTE J1810-197 (Camilo et al. 2006) Peculiarities (Mereghetti 2008): variable flux and pulse profile Flat spectra Transient in nature

  18. Levin et al. 2010

  19. Levin et al. 2012

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

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

  22. Failed predictions Failed in one new source Swift J1834.9-0856 (Tong, Yuan & Liu 2013, RAA, 13, 835; obs 2012.5/6) GBT nondetection (Esposito+ arXiv:1212.1079; obs 2011.8-11) GMRT nondetection (obs: 2013.1)

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

  24. Interesting application VLBI measurement of magnetar kick velocity: Failed predictionsXTE J1810-197: Helfand+ 20071E 1547.0-5408: Deller+ 2012J1622-4950: ?

  25. 4th radio-loud magnetar at the Galatic Center: Rea et al. 2013

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

  27. 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)

  28. Magnetar timing Kouveliotou et al. (1998) SGR 1806-20: 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)!

  29. Glitches in magnetars Glitch in AXP 1E 2259+586 (Kaspi+ 2003) Large amplitude: Accompanied by outburst Increase in spindown rate: 2 times larger

  30. Outburst of 1E 2259+586 Kaspi et al. (2003)

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

  32. Low-B magnears: two sources (-2013.7) SGR 0418+5729 (Rea+2010) Swift J1822.3-1606 (Rea+2012)

  33. SGR 0418+5729 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 Bdip<3*10^13 G(Esposito et al. 2010) One year obs: Pdot<6.0*10^-15 (P=9.1sec) Bdip<7.5*10^12 G (Rea et al. 2010, Science)

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

  35. Implications-II Assuming B-powered: Bmul>5*10^14 G

  36. Problems? Magnetar = youngNS (SNR etc) Bdip> 4.4*E13 G (braking) Bmul=10^14-10^15 G (burst and persistent emission and super-Eddington luminosity)

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

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

  39. Wind braking of magnetars Tong+2013, ApJ

  40. Wind braking of SGR 0418+5729 Tong & Xu 2012, ApJL

  41. Anti-glitch of magnetar 1E 2259+586 Archibald+ (2013), Nature

  42. Anti-glitch in SGR 1900+14 Woods+ (1999)

  43. Net spindown of PSR J1846-0258 Livingstone+ (2010) Q=8.7

  44. Modeling anti-glitch Lyutikov (arXiv:1306.2264): corona-mass-eruption-like model Tong (arXiv:1306.2445): wind braking Katz (arXiv:1307.0586): retrograde accretion Ouyed+ (arXiv:1307.1386): retrograde accreting quark-nova

  45. Wind braking Particle wind luminosity:

  46. Anti-glitch in the wind braking scenario Due to an enhanced particle wind Anti-glitch always accompanied by radiative events 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