xeus and strong gravity from black holes -...
TRANSCRIPT
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 •
!=+ "
#
#$
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