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Detecting the MRI accretion-disc instability in action

Detecting the MRI accretion-disc instability in action. Peter Wheatley University of Warwick. Movie: James Murray. Magneto-rotational instability (MRI). Balbus & Hawley 1991. Adapted from Balbus & Hawley 1998. Miller & Stone 2000. Hawley et al. Numerical MRI simulations.

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Detecting the MRI accretion-disc instability in action

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  1. Detecting the MRI accretion-disc instability in action Peter Wheatley University of Warwick Movie: James Murray

  2. Magneto-rotational instability (MRI) Balbus & Hawley 1991 Adapted from Balbus & Hawley 1998

  3. Miller & Stone 2000 Hawley et al. Numerical MRI simulations • Simulations show MRI can drive angular momentum transport • But observational handle desirable

  4. Corona should be phenomenon of the global disc

  5. Observational consequences:Hot disc corona Figure: Zdziarski & Gierlinski 2004

  6. Eclipses reveal geometry • MRI on/off states in • individual systems on • accessible timescale Cataclysmic variables • Global disc visible

  7. Low state of Z Cha XMM-Newton Wheatley & West 2003 Optical X-ray

  8. low state Patterson & Raymond 1985 Low state

  9. Optical High state EUV SS Cyg Wheatley, Mauche & Mattei 2003 X-ray

  10. low state high state Patterson & Raymond 1985 X-ray spectra

  11. NeVI Chandra LETG High state of WZ Sge Wheatley & Mauche 2005 OVI NeV NeVI FeVIII Naylor et al. 1988

  12. low state high state Patterson & Raymond 1985 X-ray spectra

  13. High state - UX UMa Pratt et al. 2004 XMM-NewtonX-ray eclipse 3-10 keV 0.3-2 keV

  14. Chandra LETG high state WZ Sge Wheatley & Mauche 2005 high state kT <= 1 keV v=840km/s RKep~2x1010cm Disappears in low state low state

  15. Conclusions • Probable detection of MRI-driven X-ray corona in CVs • Evidence includes: • Extended emission (eclipses) • Accretion disc dynamics (line widths) • Coronal temperatures (line ratios) • Absent in low state • Excellent potential to follow MRI in action

  16. EUVE spectroscopy U Gem Long et al 1996 SS Cyg Mauche, Raymond & Mattei 1995 OY Car Mauche & Raymond 2000

  17. Non eclipsing in ob, eg exosat, and others?

  18. EUVE spectroscopy U Gem Long et al 1996 SS Cyg Mauche, Raymond & Mattei 1995 OY Car Mauche & Raymond 2000

  19. outburst quiescence X-ray spectra

  20. Mauche & Raymond 2000 OY Car with EUVE WZ Sge with Chandra NeVI V~4000 km/s OVI NeV NeVI FeVIII

  21. outburst quiescence X-ray spectra

  22. kT <= 1 keV NH<<1.4x1021 cm-2 V=840km/s A(Fe)=0.2 LETG X-ray spectra kT = 6 keV NH = 1.4x1021cm-2

  23. XMM-Newton and Chandra observations of dwarf novae Peter Wheatley

  24. Overview: two topics • XMM-Newton eclipse observations: OY Car and Z Cha • Chandra spectroscopy of WZ Sge in superoutburst

  25. Wheatley & West 2003 XMM-Newton Pratt et al 1999 X-ray eclipse with ROSAT

  26. 4 3 2 1

  27. Wheatley & West, 2003 OY Car eclipse with XMM-Newton 4 1 2 3

  28. Magnetic accretion?

  29. Z Cha ROSAT light curves Van Teeseling,1997

  30. Z Cha Wheatley & West, in prep

  31. Overview: two topics • XMM-Newton eclipse observations, OY Car and Z Cha • Chandra spectroscopy of WZ Sge in superoutburst

  32. WZ Sge with Chandra Wheatley & Mauche, in prep. EUV X-ray

  33. WZ Sge with Chandra Wheatley & Mauche, in prep. EUV X-ray

  34. outburst orbital hump common superhump Optical: Patterson et al. 2002 Chandra LETG

  35. outburst quiescence Patterson & Raymond 1985 X-ray spectra

  36. Mauche & Raymond 2000 OY Car with EUVE WZ Sge with Chandra NeVI V~4000 km/s OVI NeV NeVI FeVIII

  37. outburst quiescence X-ray spectra

  38. kT <= 1 keV NH<<1.4x1021 cm-2 V=840km/s A(Fe)=0.2 LETG X-ray spectra kT = 6 keV NH = 1.4x1021cm-2

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