1 / 24

Low-magnetic-field magnetars

Low-magnetic-field magnetars. Roberto Turolla Paolo Esposito. Reporter: Fu, Lei ArXiv:1303.6052 20130506. Alternative senarios. ABCs of magnetars. Low-magnetic-field magnetars. Interpretation in the Standard model. Contents. ABCs of magnetars. Discovery of magnetars

lok
Télécharger la présentation

Low-magnetic-field magnetars

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Low-magnetic-field magnetars Roberto Turolla Paolo Esposito Reporter: Fu, Lei ArXiv:1303.6052 20130506

  2. Alternative senarios ABCs of magnetars Low-magnetic-field magnetars Interpretation in the Standard model Contents

  3. ABCs of magnetars • Discovery of magnetars • SGR(Soft Gamma repeater) • 1979.01.07-----0.25s burst from SGR 1806-20 detected • 1979.03.05-----first giant flare from SGR 0526-66 • AXP( Anomalous X-ray pulsars) • 1981---- 1E 2259+586 at the center of CTB 109 • SGR like burst was observed in 1E 2259+586, 1E 1048.1-5937 and 1E 1547-5408

  4. short bursts

  5. intermediate flares

  6. Giant flares

  7. ABCs of magnetars • Definition • a source powered by magnetic energy • variable persistent • short X/γ-ray bursts above criteria • High-B radio pulsars(HBPSRs), X-ray dim isolated neutron stars(XDINSs) • Low B magnetars

  8. Low B magnetars • SGR 0418+5729 • bursts on 2009.06.05 • persistent luminosity • spin period • period derivative • derived magnetic field • characteristic age~ 36Myr

  9. SGR 0418+5729

  10. Low B magnetars • Swift J1822.3-1606 • bursts on 2011.07.14 • 1993.09.14-15(ROSAT) • spin period • period derivative • derived magnetic field • characteristic age~ 0.8Myr

  11. Swift J1822.3-1606

  12. Interpretation in the Standard mdel • Origin of persistent emission and bursts • internal heating by magnetic field decay • Hall drift and ohmic dissipation • Ambipolar diffusion not important in superfluid core • other heating sources • twisted magnetosphere caused by the motions of star interior • small and large scale fractures in the crust

  13. Interpretation in the Standard mdel • Old magnetars • small number of bursts and comparatively low energetics • internal toroidal component decay • field decay timescale

  14. Interpretation in the Standard mdel • Numerical approach • surface magnetic field • different internal toroid component • considering only the ohmic diffusion due to numerical difficulties in treating the Hall term

  15. SGR 0418+5729

  16. Swift J1822.3-1606

  17. Outburst decay

  18. Alternative senarios • No direct measure of the surface magnetic field of magnetars • cyclotron energy of electron ~MeV • proton line • Alternative model • fossil-disc left in supernova explosion or after a CE phase • SGR 0418+5729 • initial spin period >70 ms • reach current period in • burst?

  19. Alternative senarios • Massive white dwarf (1.3-1.4 solar mass)with high magnetic field • the inertia of WD • Rotational energy losses can be • dipole magnetic field • burst activity is powered by the relief of mechanical stresses as the WD spin down(gravity overcoming centrifugal forces) • the energy release is • In order to explain the giant flare • fast spin period < 5s ? • recent calculation shows the minimum period of WD~0.3s

  20. Alternative senarios • Quark stars • degenerate debris shell co-rotating with the star or confined in a Keplerian ring • the magnetic field can reach due to the color ferromagnetism in the quark matter • spin down by magnetic braking and expels from superfluid/conducting magnetic vortices

  21. Alternative senarios • X-ray emission is powered by • magnetic decreases and reconnections • accretion of the degenerate material • Bursts is due to clumps accretion • SGR 0418-5729 • an evolved quark-ring system • characteristic age(n=4) • the magnetic field is evolve from

  22. Conclusion • The discovery of low-B magnetar has opened new perspectives in NS astrophysics • SGR 0418+5729 and Swift J1822.3-1606 are likely to be old magnetars with strong internal toroidal field • 20% of Galactic radio pulsars have a dipole field higher than SGR 0418+5729 may show up as a transient magnetar

  23. 点击添加标题 点击添加标题 点击添加标题 点击添加标题 点击添加标题 点击添加标题 文本 文本 文本 文本 文本 添加文本

More Related