The Broad Iron Line Profile ofXTE J1650-500

DOM WALTON

IoA, Cambridge, UK

In collaboration with

Rubens Reis, Ed Cackett, Jon Miller and Andy Fabian

Berlin: 2011

BLACK HOLE ACCRETION

Dom Walton

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Berlin: 2011

AGN SPECTRA

1H 0707-495 - Zoghbi et al. (2010)

(see also Fabian et al. 2004, Boller et al. 2002, etc.)

Dom Walton Berlin: 2011

BLACK HOLE ACCRETION

Dom Walton

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Berlin: 2011

DISC REFLECTION

Dom Walton

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Berlin: 2011

RELATIVISTIC EFFECTS

Dom Walton

Characterising the reflection component is one way in which we can measure BH spin

Fabian et al. (2000)

Berlin: 2011

BLACK HOLE BINARIES

Spectra obtained from Galactic black hole binaries (BHBs) show the same primary continuum components as AGN:

Many also display broad excesses at ~6 keV

BHBs are brighter due to their proximity, so any absorption features can be well constrained

Thermal emission (accretion disc, low energy)

Comptonised emission (corona, high energy)

Dom Walton Berlin: 2011

XTE J1650-500

Dom Walton

2001 outburst observed by XMM (burst mode, x1) and BeppoSAX (x3)

Displays a broad excess at ~6 keV, independent of Comptonised continuum model:

Gaussian: σ = 1.2 ± 0.2 keV Laor: R

in = 1.5 ± 0.1 R

G

Berlin: 2011

XTE J1650-500

Dom Walton

2001 outburst observed by XMM (burst mode, x1) and BeppoSAX (x3)

Displays a broad excess at ~6 keV, independent of Comptonised continuum model:

Note residual instrumental features at ~1.8 and 2.2 keV

Gaussian: σ = 1.2 ± 0.2 keV Laor: R

in = 1.5 ± 0.1 R

G

Berlin: 2011

DISC REFLECTION MODEL

REFBHB (Ross & Fabian, 2007); Rin ~ 2 R

G

Dom Walton

- Powerlaw- Relativistic disc reflection (incl. thermal continuum)

Berlin: 2011

SOFT RESIDUALS

Soft residuals at ~0.8 keV persist. Possible astrophysical origins:

Comparison with burst mode Crab data shows similar residuals, so likely to be systematic

Doesn't effect inner radius obtained (always ~2 RG)

• Additional reflected OVIII emission and/or Neon absorption in the ISM

• Local ionised absorption (disc wind)

Dom Walton Berlin: 2011

INSTRUMENTAL EFFECTS

Dom Walton

Comparison with contemporaneous BeppoSAX MECS data (obtained ~1 day prior to XMM observation):

The line profile is independent of detector type (MECS detectors are gas based)

Profile is not significantly modified by instrumental effects

There are claims the line profiles obtained could be broadened and skewed by instrumental effects, e.g. pile-up, charge transfer inefficiency.

Berlin: 2011

COMPTON BROADENING

Dom Walton

Electron temperature (~6 keV) and optical depth (~1) required to broaden the line in the corona are not consistent with those found for the continuum

Also expect the line centroid energy to increase by ~0.35 keV, but E

G < 6.5 keV

Compton broadening in the disc is self-consistently included in REFBHB

'Windline' models run into problems with the mass outflow rates required

Berlin: 2011

LINE PROFILE EVOLUTION

Dom Walton

Latter two BeppoSAX observations were obtained later in the evolution of the outburst

Line profiles obtained do not show significant deviations from early BeppoSAX and XMM observations

This is not consistent with the expected behaviour for scenarios dominated by electron scattering

Berlin: 2011

XTE J1650-500 SPIN

0.84 ≤ a* ≤ 0.98 (90% confidence)

Dom Walton Berlin: 2011

MCG -6-30-15

Seyfert 1.2 AGN, 350 ks XMM observation taken in 2001

Spectrum complicated by a warm absorber, accounted for by the model of Chiang & Fabian (2011)

Also displays a broad excess at ~6 keV

Dom Walton

Absorption model includes:

Fast, highly ionised component 2 slow, lower ionisation components Iron-L dust absorption

Berlin: 2011

LINE PROFILES

Dom Walton Berlin: 2011

LINE PROFILES

Dom Walton Berlin: 2011

COMMON ORIGIN

As the excesses at ~6 keV broad iron lines observed in AGN and BHBs are similar, we would like to find a common physical origin for them.

Absorption does not (usually) significantly modify the spectra of BHBs

Reflection from the inner accretion disc is the only viable common interpretation

Dom Walton Berlin: 2011

SUMMARY

Dom Walton

The BHB XTE J1650-500 displays a broad iron line profile (see also earlier works by Miller+ 2002, 2009, Miniutti+ 2005)

The line profile requires that the emission arises in the regions of strong gravity close to the black hole, and is similar to those seen in AGN

As BHBs provide an unobscured view of the accretion flow, relativistic disc reflection must be a fundamental process in the disc-corona geometry

Comparison with BHBs therefore provides a strong argument in favour of the presence of relativistic disc reflection in AGN

Berlin: 2011

EPFAST

Dom Walton

EPFAST attempts to correct for the features at ~2 keV; applies an energy independent correction

CTI is energy dependent (CTI ~ E-0.5); EPFAST over-corrects at iron K energies

EPFAST

Berlin: 2011