measuring the black hole spin of gx 339-4: a systematic look at its very high and low/hard state....
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Measuring the black hole spin of Measuring the black hole spin of GX 339-4: A systematic look at its GX 339-4: A systematic look at its
very high and low/hard state.very high and low/hard state.
Rubens ReisRubens ReisInstitute of Astronomy - CambridgeInstitute of Astronomy - Cambridge
In collaboration with Andy Fabian, Randy Ross, Giovanni Miniutti, Jon Miller and Chris Reynolds
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 With XMM-Newton we can now obtain precise spin for these systems spin for these systems
IntroductionIntroduction: : GeometryGeometry
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 ???
And a modest sketch of the region close to the black hole
rin
rout
Prograde rotation
Constraining the spin of GX 339-4
PLC
RDC
IntroductionIntroduction: : Spectral ComponentsSpectral Components
Thermal or Very High state (VHS)
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).
Constraining the spin of GX 339-4
Figure adapted from Zdziarski & Gierlinski 2004
IntroductionIntroduction: : Spectral ComponentsSpectral Components
... and similarly in the Low Hard state (LHS)
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.
Constraining the spin of GX 339-4
Figure adapted from Zdziarski & Gierlinski 2004
Introduction:Introduction: Fe Kα line and reflection behaviour in extreme gravity
Constraining the spin of GX 339-4
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
Introduction:Introduction: Fe Kα line and reflection behaviour in extreme gravity
Constraining the spin of GX 339-4
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.
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).
Model:Model: Spin from standard assumptionSpin from standard assumption
Constraining the spin of GX 339-4
The effect gravity has on the reflection profile becomes more prominent the closer the emission is to the event horizon (Fabian et al. 1989).
The radius of the innermost stable circular orbit Rms depends on the spin. (Bardeen et al. 1972).
Figure adapted from Bardeen et al. 1972
rms
Model:Model: Spin from standard assumptionSpin from standard assumption
Constraining the spin of GX 339-4
The effect gravity has on the reflection profile becomes more prominent the closer the emission is to the event horizon (Fabian et al. 1989).
Figure adapted from Bardeen et al. 1972
rms
Fit the reflection, obtain rFit the reflection, obtain rinin = r = r
ms ms SPINSPIN
The radius of the innermost stable circular orbit Rms depends on the spin. (Bardeen et al. 1972).
Constraining the spin of GX 339-4
Model: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).
Model:Model: Self-consistent reflection
Constraining the spin of GX 339-4
Mid-plane kTBB
H = half-thickness of discFdisc
Emergent flux
Disc surface, ГT = 10
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
Constraining the spin of GX 339-4
Results:Results: Fits with simple modelFits 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.
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 = r
g
Constraining the spin of GX 339-4Results:Results: Fits with reflection Fits with reflection
modelmodel 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 r
g
0.170.102.08
Constraining the spin of GX 339-4
Results:Results: Broadband fits with reflection modelBroadband 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 )
Constraining the spin of GX 339-4
Results:Results: Different disc ionisation...Different disc ionisation... VHS LHS
rin = r
g (90% confidence)
Constraining the spin of GX 339-4
Results:Results: ......Similar disc geometrySimilar disc geometry
rin = 2.03 ± 0.03 r
g (90% confidence)
VHS LHS
0.170.102.08
Assume rAssume rinin = r = r
msms
Constraining the spin of GX 339-4
Results:Results: ......Similar spin parameterSimilar spin parameter
VHS
LHS
Constraining the spin of GX 339-4
Results:Results: ......Similar spin parameterSimilar spin parameter
VHS
LHS
Constraining the spin of GX 339-4
Results:Results: ......Similar spin parameterSimilar spin parameter
VHS
LHS
Spin:0.935 ± 0.01 (statistical)
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
Constraining the spin of GX 339-4
Summary: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)
Constraining the spin of GX 339-4
Future work: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
Constraining the spin of GX 339-4
Summary: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)