Measuring the black hole spin of GX 339-4: A systematic look at its very high and low/hard state.

1. Measuring the black hole spin of GX 339-4: A systematic look at its very high and low/hard state. Rubens ReisInstitute of Astronomy - Cambridge In collaboration withAndy Fabian, Randy Ross, Giovanni Miniutti, Jon Miller and Chris Reynolds

2. Constraining the spin of GX 339-4 Black holes (BH) can be characterised by two observable parameters: Mass and spin Over 20 stellar mass BH binaries have known mass (Remillard & McClintock 2006) With XMM-Newton we can now obtain precise spin for these systems

3. Constraining the spin of GX 339-4 Introduction: Geometry An artist's view of an X-ray binary (GX 339-4?) from far, far away... Mass > 6.0 solar mass (Hynes et al. 2003)‏ Spin ??? PLC RDC rin And a modest sketch of the region close to the black hole rout Prograde rotation

4. Constraining the spin of GX 339-4 Introduction: Spectral Components Thermal or Very High state (VHS)‏ Figure adapted from Zdziarski & Gierlinski 2004 Quasi-thermal blackbody emission from accretion disc. Fluxdisc ≥ 75%. Powerlaw possibly due to Compton upscattering of soft disc photons in a hot thermal/nonthermal corona. Hard X-ray source illuminates the disc and gives rise to Compton reflection and Fe Kα fluorescence (amongst other things).

5. Constraining the spin of GX 339-4 Introduction: Spectral Components ... and similarly in the Low Hard state (LHS)‏ Figure adapted from Zdziarski & Gierlinski 2004 Quasi-thermal emission from accretion disc decreases to Fluxdisc ≤ 20%. Contribution from Comptonisation increases and a cut-off between 100-200 keV is now present. The Fe Kα fluorescence line is now narrower and more distinct.

6. Constraining the spin of GX 339-4 Introduction: Fe Kα line and reflection behaviour in extreme gravity An intrinsically narrow emission line shows a double-peak profile from annuli in a non-relativistic Newtonian disc. Transverse Doppler shift makes the profile redder and beaming enhances the blue peak. Closer to the black hole the overall profile is shifted to the red side and the blue peak is reduced. Figure from Fabian et al. 2000

7. Constraining the spin of GX 339-4 Introduction: Fe Kα line and reflection behaviour in extreme gravity An intrinsically narrow emission line shows a double-peak profile from annuli in a non-relativistic Newtonian disc. Transverse Doppler shift makes the profile redder and beaming enhances the blue peak. Closer to the black hole the overall profile is shifted to the red side and the blue peak is reduced. In the inner regions of an accretion disc the resulting Fe Kα line profile is highly skewed and broad (Fabian et al. 1989). Figure from Fabian et al. 2000 These effects are important for ALL of the reflection signatures and not limited to the Fe Kα line profile.

8. Constraining the spin of GX 339-4 Model:Spin from standard assumption The effect gravity has on the reflection profile becomes more prominent the closer the emission is to the event horizon (Fabian et al. 1989). rms Figure adapted from Bardeen et al. 1972 The radius of the innermost stable circular orbit Rms depends on the spin. (Bardeen et al. 1972).

9. Constraining the spin of GX 339-4 Model:Spin from standard assumption The effect gravity has on the reflection profile becomes more prominent the closer the emission is to the event horizon (Fabian et al. 1989). rms Figure adapted from Bardeen et al. 1972 The radius of the innermost stable circular orbit Rms depends on the spin. (Bardeen et al. 1972). Fit the reflection, obtain rin = rms SPIN

10. Constraining the spin of GX 339-4 Model:Self-consistent reflection • The X-ray spectrum of black hole binaries (BHB) in the thermal/VHS have usually been fitted with a combination of: • an ionised disc reflection component, • Laor relativistic line (Laor 1991) and • a multicolour disc blackbody (usually diskbb, Mitsuda et al. 1984).

11. Constraining the spin of GX 339-4 Model:Self-consistent reflection • The X-ray spectrum of black hole binaries (BHB) in the thermal/VHS have usually been fitted with a combination of: • an ionised disc reflection component, • Laor relativistic line (Laor 1991) and • a multicolour disc blackbody (usually diskbb, Mitsuda et al. 1984). • We employed the self-consistent reflection model developed by Ross & Fabian (2007) where blackbody radiation entering the accretion disc surface from below is implicitly included. Illuminating flux from disc corona Emergent flux Disc surface, ГT = 10 H = half-thickness of disc Fdisc Mid-plane kTBB

12. Constraining the spin of GX 339-4 Results:Fits with simple model Simple model consisting of power-law and diskbb The broad Fe Kα line and in the case of the VHS the Kα edge is clearly seem.

13. Constraining the spin of GX 339-4 Results:Fits with reflection model VHS. Model assuming a broken power-law emissivity profile (Rbreak = 4.9 rg )‏ χ2/υ = 2237.8/ 1653 (1.35)‏ Log(ξ) ≈ 4.2 ( ξ in ergs cm s-1 )‏ rin = 2.03 ± 0.03 rg • LHS. Fitted with reflection model above 2 keV. • Ignored thermal emission χ2/υ = 2242.5 / 2031 (1.1)‏ • Log(ξ) ≈ 3.1 ( ξ in ergs cm s-1 )‏ • rin = rg

14. Constraining the spin of GX 339-4 Results:Broadband fits with reflection model VHS. Model assuming a broken power-law emissivity profile (Rbreak = 4.9 rg )‏ χ2/υ = 2549.3/ 1718 (1.48)‏ LHS. χ2/υ = 2316.6 /2095 (1.11)‏ Log(ξ) ≈ 3.1 ( ξ in ergs cm s-1 )‏

15. Constraining the spin of GX 339-4 Results:Different disc ionisation... VHS LHS

16. Constraining the spin of GX 339-4 Results:...Similar disc geometry VHS LHS rin = 2.03 ± 0.03 rg (90% confidence)‏ rin = rg (90% confidence)‏ Assume rin = rms

17. Constraining the spin of GX 339-4 Results:...Similar spin parameter VHS LHS

18. Constraining the spin of GX 339-4 Results:...Similar spin parameter VHS LHS

19. Constraining the spin of GX 339-4 Results:...Similar spin parameter VHS LHS Spin: 0.935 ± 0.01 (statistical)

20. Constraining the spin of GX 339-4 Recent work on Suzaku data of GX 339-4 in the intermediate state (Miller et al. 2008) resulted in a spin parameter of: 0.93 ± 0.01 (statistical) ± 0.04 (systematic)‏ Figure from Miller et al. 2008

21. Constraining the spin of GX 339-4 Summary: • The obvious differences in the spectra of the two states are due to differences in the ionisation state of the disc ( Ross & Fabian 1993)‏ • For the VHS, it is particularly important to use a reflection model that fully accounts for the effects of Compton scattering. • The spin parameter in GX 339-4 was found to be the same in both low hard and very high spectral states • With XMM-Newton we were able for the first time to measure the spin of a stellar mass black hole to a high level of accuracy in two distinct states. Using a self-consistent reflection model we were able to infer the spin parameter of GX 339-4 to be: 0.935 ± 0.01 (statistical) ± 0.01 (systematic)‏

22. Constraining the spin of GX 339-4 Future work: Measure spin in AGN using reflection model PI: A.C.Fabian et al. Explain the rapid and complex variability in the frame-work of reflection

23. Constraining the spin of GX 339-4 Summary: • The obvious differences in the spectra of the two states are due to differences in the ionisation state of the disc ( Ross & Fabian 1993)‏ • For the VHS, it is particularly important to use a reflection model that fully accounts for the effects of Compton scattering. • The spin parameter in GX 339-4 was found to be the same in both low hard and very high spectral states • With XMM-Newton we were able for the first time to measure the spin of a stellar mass black hole to a high level of accuracy in two distinct states. Using a self-consistent reflection model we were able to infer the spin parameter of GX 339-4 to be: 0.935 ± 0.01 (statistical) ± 0.01 (systematic)‏