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Accretion and reflection in Galactic BHs and AGNs

Explore the X-ray reflection spectrum and relativistic effects in accreting black holes and active galactic nuclei (AGNs), including the broad Fe line and absorption models. Investigate the soft excess problem and its possible interpretations. Study disc reflection in X-ray binaries.

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Accretion and reflection in Galactic BHs and AGNs

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  1. Accretion and reflection • in Galactic BHs and AGNs • Giovanni Miniutti • Lab. Astroparticule et Cosmologie - Paris The X-ray Universe 2008 - Granada

  2. Accreting black holes: the X-ray view Soft excess Power law X-ray reflection e.g. Fabian & Miniutti 07 (CUP review) • all modified by absorption (Galactic and/or local)

  3. The X-ray reflection spectrum PLC RDC Reynolds 96

  4. The X-ray reflection spectrum • this is the X-ray reflection • spectrum in the rest frame of • the emitting gas • however, if emission comes from the accretion disc one has • to consider: • the strong gravity of the BH • the fast orbital motion close to the center

  5. X-ray reflection: relativistic effects • Doppler shifts Fe K • relativistic beaming • gravitational redshift intensity • gravitational light bending energy

  6. ISCO vs spin • Kerr/Schwarzschild X-ray reflection: relativistic effects

  7. X-ray reflection: relativistic effects rest frame spectrum observed spectrum

  8. The broad Fe line of MCG-6-30-15 Fabian et al 02; Vaughan & Fabian 04 Tanaka et al 95

  9. The broad Fe line of MCG-6-30-15 Suzaku Miniutti et al 07

  10. Suzaku Suzaku Fe xxv Fe xxvi Fe xxv Fe xxvi XMM Miniutti et al 07 The broad Fe line of MCG-6-30-15 • The broad Fe line first detected by ASCA was later confirmed by all subsequent X-ray missions • The latest observation was performed with the Suzaku observatory

  11. Other possible interpretation ? • Spectral curvature in the Fe K band + excess above 10 keV can also be reproduced with (rather complex) absorption models: • 3 different emission components + • 5 different absorption zones: only 2 are global ( and gratings-detected) Miller et al 08

  12. Other possible interpretation ? • The claim is that with this model one can relax the requirement for a high reflection fraction and that things are consistent with R=1-2 • However … for R=1-2 Fref / Fpl (20-40 keV) ~ 0.4-0.8 • while from the plot we get ~ 2 ! Miller et al 08

  13. IRAS 13197-1627 with XMM-Newton • Absorption is sometimes unambiguous • In these cases, can we disentangle between broad Fe lines and absorption? Miniutti et al 07

  14. IRAS 13197-1627 with XMM-Newton • 2-12 keV band: an absorbed Compton-thin (4 x 1023 cm-2) AGN, but • Fe K is resolved ( ~ 100 eV, somehow strange for absorbed AGNs) • Transmitted Fe K EW and Fe edge suggest Fe is 1.5 x Solar • Negative residuals in the 6.7-7.2 keV band • Positive residuals > 10 keV and in 5-6 keV band

  15. Resolved Fe K line • Unresolved Fe K line IRAS 13197-1627 with XMM-Newton • A different way of looking at the residuals: use a Gaussian filter

  16. IRAS 13197-1627 with XMM-Newton • A reflection component from the disc potentially could explain both the positive and negative residuals with a broad Fe line and broad Fe edge

  17. IRAS 13197-1627 with XMM-Newton • We obtain a very significant improvement and running the Gaussian filter once again gives • The residual abs line • is at 6.81 keV • If Fe xxv this implies an outflow with 5000 km/s • But zc=5000 km/s …. • … so we cannot exclude a Galactic origin (McKernan et al 05)

  18. NGC 1365 with XMM-Newton Risaliti et al in prep

  19. NGC 1365 with XMM-Newton • Similar but with a C-thick cloud • XMM simulation XEUS simulation

  20. The “soft excess problem” • The SE is just a definition: • Excess emission with respect to the low-E extrapolation of the 2-10 keV model (power law) • Easiest interpretation: • High-E tail of the disc quasi-BB thermal emission • However, too many problems affect that interpretation

  21. The “soft excess problem” • The “temperature” is too hot and too uniform to be real disc BB emission • Several different ideas, but mainly: • Absorption by a relativistic wind (Gierlinski & Done 04 + …) • Reflection from the disc (Crummy et al 06 + …)

  22. The “soft excess problem”

  23. The “soft excess problem” • 1H 0707-495: a reflection-dominated NLS1 (other interpretations possible) • (Boller et al 02; Fabian et al 02, 05; Gallo et al 05)

  24. The “soft excess problem” • the X-ray spectrum can be modelled withonly two components

  25. The “soft excess problem”

  26. The “soft excess problem” • In the case of 1H 0707-495 the light bending model explains • the reflection-dominated spectrum • the Fe K line shape • the variability of the two main spectral components

  27. Miller 04, 07 What about X-ray binaries? • In recent years, many examples of disc reflection from BH binaries have been detected

  28. What about X-ray binaries? • Most cases (but not all !) during VHS or IS • Miller et al 05

  29. What about X-ray binaries? • “Broad Fe line detection is model dependent” • Miller et al 08

  30. What about X-ray binaries? • XTE J1650-500 • XTE J1650-500 • Belloni et al 04 • Miniutti et al 04

  31. What about X-ray binaries? • XTE J1650-500 • XTE J1650-500 • Miniutti et al 04; Fabian & Miniutti 08 • Belloni et al 04

  32. Truncated disc in hard state? • GX 339-4 Fe line does not agree with the idea… • Miller et al 06

  33. Truncated disc in hard state? • GX 339-4 Fe line does not agree with the idea … • The thermal disc in the hard state + its temperature and luminosity suggest that it extends down to the ISCO (or close) • Miller et al 06 • Reis et al 08

  34. Truncated disc in hard state? • GX 339-4 Fe line does not agree with the idea … • The Fe line is in fact so broad that it also consistently suggests a disc extending down to the ISCO even in the hard state • Miller et al 06 • Reis et al 08

  35. Truncated disc in hard state? • Independent fits to the VHS and to the Hard state with complete ref models yield to consistent inner disc radii in both cases (ISCO? If so, very precise spin measurement) • Reis et al 08

  36. Truncated disc in hard state? • Maybe GX 339-4 is somewhat unique? • The truncated disc idea was mainly (not only) based on the absence of a thermal disc in the hard state • XMM+RXTE obs of the newly discovered BH candidate • SWIFT J1753.5-0127 • RXTE -> strong band-limited noise typical of hard state(LX/Ledd~0.003)  ~ 1.65 • Miller et al 07 • The Fe line is in fact so broad that it suggests a disc extending down to the ISCO even in the hard state • Can the transitions occur with a stable disc at the ISCO?

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