XEUS andStrong Gravity from

Black Holes AC Fabian IoA Cambridge UK

With help from Giovanni Miniutti, Jon Miller,Chris Reynolds, Rubens Reis and Randy Ross

Accretion makes massive blackholes

2

1)1( cz •

!=+ "

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Soltan 82

Mean redshift Radiative efficiency

Light Mass density in BH

η > 0.1Observations

Much of the radiation originates within 6Rg

Strong Gravity Effects

• Gravitational redshift• Gravitational light bending• Dragging of inertial frames in

Kerr metric (ISCO depends onBH spin)

Information from spectra andvariability

• X-ray ‘reflection’ givesimportant clues in thespectrum

• Variability timescalesand spectral changesshow differentspectral components

Reflection from photoionized matter(Ross & Fabian 93, 05)

Also see Young+, Nayakshin+, Ballantyne+, Rozanska+, Dumont+

Schwarzschild

Kerr

Fabian+89, Laor 90…Dovciak+04; Beckwith+Done05

Suzaku

Strength and behaviour of line impliesGRAVITATIONAL LIGHT BENDING

MCG-6-30-15

Red wing due to largegravitational redshift

implying BH rapidly spinning

Incidence of broad lines in XMM database Guainazzi+06 (see also Nandra+06)

Emphasises needfor good data

Broad lines found in>50% of spectra with

>150,000 counts

Not just a line but wholereflection spectrum

Add relativistic blurring

Soft excess – broad iron line – Compton hump

Crummy+05 22 PG QSO +12 Seyf1

Soft Excesses

MCG-6 Suzaku: Miniutti+06

Observed reflection requires strong iron emission line

Probing Black Hole Spin

Assumption: measurements of rms determine (or constrain) a

ISCO conjecture• Measure Rin from spectra ⇒ RISCO ⇒ spin?• B decreases Rin (Begelman & Reynolds, Gammie,

Krolik, Hawley…)??• BUT low ionization ⇒thin, slowly accretion disc,

which is not plunging, so Rin ~ RISCO

Computations show that Rin measured from iron lineis within ~0.5rg of Risco (Reynolds & Fabian 07)

Density

Azimuthal field

Reynolds & Fabian 07 in press

Reynolds & Fabian (ApJ in press)

Assume illumination bysource on symmetry axis

of accretion disk atDs=6rg

Reynolds & Fabian (ApJ in press)

Primary method… measure black hole spinusing the width/profile of the broad iron

line…Non-spinningRapidly-spinning

KERRDISK modelBrenneman & Reynolds (2006)

GX339-4 Miller et al 04,07

LSVHS

J. MillerSuzaku J Miller submitted

GX339-4

Galactic BH:Disk hot, so line

Comptonized

Ross+Fabian07

GBH

AGN

GX339-4withXMM

R Reis

• Main point here is to demonstratethat we are seeing the accretion flowat ~2rg in several objects.

• This requires a rapidly spinning blackhole.

• Precise determination of spin requiresmodelling of flows and systematics.Current work suggests

~5%.

XEUS z=0.5

How does it vary?

Iwasawa+ Shih+ Fabian+ Vaughan+ McHardy+ Uttley+ Reynolds+

Variable power-law

Quasi-constant reflection-dominated component

Schematic picture of the two-componentmodel

Data consistent withhighly variable power-law + quasi-constant reflection

spectrum

Difference spectrum: (High flux)-(Low flux)

is a power-law modified by absorption

1 keV 10 keV

So we know which large scale features are due to absorption

Ratio to power-law

Light bending model in Kerrspacetime

Miniutti et al 03; Miniutti & Fabian 04; earlier work by Matt+see also Tsuebsuwong, Malzac+06

MCG-6 XMM 2000+2001 dataLarsson+06

Variability

RMS fractional variability spectrum

Mkn 335 2007 low state Grupe+07submitted

• Broad iron lines enable the determinationof black hole spin

• Also enables study of the accretion flowand strong gravity effects (redshift andlight bending) of extreme gravity – howgravity works and powers quasars

• Next stage requires more photons fromAGN (which are relatively MUCH brighterthan GBH on a “per-light-crossing-time”basis)

• This implies next generation X-raytelescopes

Armitage & Reynolds

Arcs trace orbits ofdisk material aroundblack hole… can be

compared withpredicted GR orbits

Iron line intensity as function of energy and time.

Theoretical

Orbiting hot spots

Andy Young andChris Reynolds

M=107 MsunF2-10=5×10-11

a=0.998

Reverberation

Brightest lines are about 2 ph m-2 s-1

Need sources with high L/LEdd for broad lines(NLS1/GXRB)

Typically means•BH mass of 106-108 Msun•or timescales of 100s to 104s.

Therefore to study such BH on theirintrinsic variabilitylight crossing timescalesinner orbital period

⇒ effective collecting area at 6 keV in m2 class

XEUS has have the potential tomaker MAJOR advances