1 / 29

Wind accretion in SGXBs

Wind accretion in SGXBs. Negueruela arXiv: 0907.2883v1 Reporter:zhangzhen 09.09.22. Aim. A review about the possible formation of accretion disks in OB X-ray binary systems Points: Spin evolution Wind accretion Disk formation

haruko
Download Presentation

Wind accretion in SGXBs

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. Wind accretion in SGXBs Negueruela arXiv: 0907.2883v1 Reporter:zhangzhen 09.09.22

  2. Aim • A review about the possible formation of accretion disks in OB X-ray binary systems • Points: Spin evolution Wind accretion Disk formation Simulation

  3. Outlines • Introduction: Something about HMXBs The theory of wind accretion • Analisis about the theoty Real wind Real accretion • Case study GX 301-2 SFXT

  4. Introduction

  5. Types of HMXBs • Corbet 1986

  6. The theory of wind accretion • Bondi-Hoyle-Lyttleton accretion the supersonic motion of a point mass through a gas cloud then

  7. Modification

  8. The need for more consideration • X-ray light curves (Ribo et al. 2006)

  9. Spin variation: Vela X-1 (Bildsten et al. 1997)

  10. Spin variation: 4U 1907+09 (Fritz et al.2006)

  11. Aspects of modification • The wind of massive stars are highly structured • Accretion on to a very small object is an unstable process • The magnetic field of the neutron star may affect the flow of material

  12. Wind structured: clump • Observation: large-scale cyclical structures (Kaper & Fullerton 1998 Springer) • Simulations (runacres & Osocki 2002) • OB star spectra (Prinja et al. 2005) • H profile of O-type star (Markova et al. 2005) • No direct obsevational evidences • Not smooth, constant density

  13. Runacres & Owocki 2004

  14. Wind structured: overall geometry • Equatorialy enhanced mass loss (Markove et al. 2005; Ud-Doula et al. 2005) • Poles enhanced mass loss (Smith & Townsend 2007)

  15. Accretion: unstable process • Bow shock (Nagae et al. 2005)

  16. Flip-flop oscillation 2D simulation (Matsuda et al. 1987)

  17. Flip-flop oscillation 3D simulation: stable flow (Ruffert et al. 1999; Kryukov et al. 2005) flip-flop oscillation ---- a numerical artifact a review: Foglizzo et al. 2005 flip-flop instability ---- physical origin the coupling of advected perturbation to acoustic waves

  18. 2D simulation: the smaller the accretor, the more unstable (Blondin & Pope 2009)

  19. Photo-ionisation • Emitting X-ray  ionising the heavy elements  slowing down the wind  increasing the accretion radius (Blondin et al. 1991) • Wind lines orbital variability (Kaper et al. 1993) • Far ultra violet spectra of the counterpart to 4U 1700-37 (Iping et al.2007)

  20. Magnetid field • Anzer & Borner 1995 • Explain Vela X-1 • Spin fluctuation

  21. Case study

  22. GX 301-2 • Feature: Wide: Porb=41.5d Eccentric: e=0.45 Companion: B1 Ia+ hypergiant Denser, slower wind Flux: ~4 times higher close to periastron Peaking 1-2d before periastron

  23. Explanation for GX 301-2 • The size of the hypergiant may be very close to filling its Roche lobe at periastron allowing the formation of an accretion stream (Koh et al. 1997) • The existence of such a stream in optical spectra of the companion (Kaper et al. 2006) • The average X-ray lightcurve can be fit by accretion from a spherical wind and an accretion disk (Leahy & Kostka 2008)

  24. Supergiant fast X-ray transients • Brief outbursts with a rise timescale of tens of minutes and lasting only a few hours • OB supergiants • Lx 10^36erg/s at the peak of the outbursts Lx 10^33~10^35erg/s outside the outbursts • Spectra and lightcurves: wind accretion

  25. Sugera et al. 2006

  26. Explanation for SFXT • Clumps: In’t Zand (2005) Walter & Zurita Heras (2007) • Thin circumstellar disk surrounding the supergiant (Sidoli et al. 2007) • Interaction of the wind and the magnetosphere (Grebenev & sunyaev 2007) • Kreykenbohm et al. 2008

  27. Summary • Bondi-Hoyle-Lyttleton accretion • Modification: Clump Flip-flop oscillation • Example GX 301-2 SFXT

  28. Thanks

More Related