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Modelling the high mass accretion rate spectra of GX 339-4

Modelling the high mass accretion rate spectra of GX 339-4. Mari Kolehmainen & Chris Done Durham University Maria Diaz Trigo, ESO. High Energy View of Accreting Objects: X-ray Binaries Agios Nikolaos, Crete 2010. High mass accretion rate spectra. classical high/soft state disc dominated

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Modelling the high mass accretion rate spectra of GX 339-4

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  1. Modelling the high mass accretion rate spectra of GX 339-4 Mari Kolehmainen & Chris Done Durham University Maria Diaz Trigo, ESO High Energy View of Accreting Objects: X-ray Binaries Agios Nikolaos, Crete 2010

  2. High mass accretion rate spectra • classical high/soft state • disc dominated • measure BH spin from disc continuum • very high/intermediate state • strong hard X-ray tail • measure BH spin from Fe-line profile

  3. Beyond the RXTE energy band 3 keV GX 339-4

  4. GX 339-4 • 5.8 < M< 15 M D > 6 kpc 45°< i < 70° • Loads of RXTE data (> 3 keV) • Few XMM-Newton EPIC-pn Burst mode observations (> 0.7 keV) • not piled up!

  5. EPIC-pn Burst mode • Time resolution 7μs • Timing mode 30μs (800 counts/s) • Pileup limit 60,000 counts/s • Duty cycle 3 % • photon collecting time/readout time • Extracted using SAS10 • includes CTI correction

  6. Burst mode observations of GX 339-4 • joint EPIC-pn/RXTE observations • 2 disc dominated states • 2 soft intermediate states (SIMS)

  7. Burst mode observations of GX 339-4 M = 10 M D = 8 kpc i = 60° 0156760101 (SIMS) 0410581201 (discy) 0410581301 (SIMS) 0410581701 (discy) Kolehmainen & Done (2010)

  8. Continuum fitting below 3 keV: Disc dominated state • DISKBB • simplest multi-colour disc blackbody • KERRBB • stress-free inner boundary condition, relativistic smearing and the colour- temperature correction • BHSPEC • calculates radiative transfer through each disc annuli • includes all the relativistic corrections • assumes Rin=RISCO 3 keV

  9. Continuum fitting below 3 keV: Disc dominated state • Disc model • use this as seed photons for Comptonisation (convolved with Simpl (Steiner et al. 2009))to make X-ray tail • reflection of Comptonised continuum using ionised reflection models of Ross & Fabian • relativistic smearing (kdblur)

  10. Continuum fitting below 3 keV: Disc dominated state • diskbb+reflection • very steep continuum to make disc broader • Γ > 3 • reflection fraction ~4 • misses HEXTE

  11. Continuum fitting below 3 keV: Disc dominated state • diskbb+reflection • very steep continuum to make disc broader • Γ > 3 • reflection fraction ~4 • misses HEXTE

  12. Continuum fitting below 3 keV: Disc dominated state • diskbb+CompTT+ reflection • Γ~2.4 • reflection fraction~0.4 • extrapolates to HEXTE

  13. Continuum fitting below 3 keV: Disc dominated state • diskbb+CompTT+ reflection • Γ~2.4 • reflection fraction~0.4 • extrapolates to HEXTE

  14. Continuum fitting below 3 keV: Disc dominated state • bhspec+reflection • Γ~2.3 • reflection fraction ~0.9 • extrapolates to HEXTE • does not allow SIMS fitting

  15. Continuum fitting below 3 keV: Disc dominated state • bhspec+reflection • Γ~2.3 • reflection fraction ~0.9 • extrapolates to HEXTE • does not allow SIMS fitting

  16. Continuum fitting past the disc dominated state: The model • tbabs*((diskbb*simpl)+CompTT+kdblur*refxion*(simpl*diskbb)) • a major advantage comes from being able to fit with different mass accretion rates disc dominated

  17. Continuum fitting past the disc dominated state: The model • tbabs*((diskbb*simpl)+CompTT+kdblur*refxion*(simpl*diskbb)) • a major advantage comes from being able to fit with different mass accretion rates SIMS

  18. The soft intermediate state (SIMS) • 20-25% of disc up-scattered to produce tail • photon index 2.44 • no high energy roll-over • frac. of reflected emission ~0.5 • Rin~ 70Rg • highly ionised • So what about the Fe-line? Obsid 0410581301

  19. The Fe-line and the BH spin Previously derived an upper limit of 0.9 for the spin in GX 339-4 from continuum fitting of disc dominated RXTE spectra GX 339-4 widely studied in terms of Fe-line • burst mode spectrum gave a*= 0.935 (Miller et al. 2004; Reis et al. 2008)

  20. The Fe-line and the BH spin Obsid 0156760101 diskbb+po+reflection • disc, power law, ionised smeared reflection • continuum modelled by ignoring 4−7 keV Residuals show a broad iron line

  21. The Fe-line and the BH spin Obsid 0156760101 diskbb+compTT+reflection • convolved disc, compTT, ionised smeared reflection • Narrow line does not constrain BH spin

  22. Conclusions • The XMM-Newton Burst mode can actually be used to make science • can look at the disc below 3 keV even with the brightest objects • Real disc spectra are much broader than diskbb • Changing the continuum model changes the shape of the iron line (and the BH spin)

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