SUMMARY

PROBING STRONG GRAVITY IN AGN

Kirpal NandraImperial College London

PROBING STRONG GRAVITY

• The Promise• The Probes• The Progress• The Problems• The Prospects• Probably…

PaulReviewsObservations (and Theory)

THE PROMISE

• What are the processes close to the event horizon?• Are black holes in AGN spinning?• How does BH spin evolve on the Cosmic Scale?• How does matter behave in the strong field?• Does it obey the predictions of GR?

THE PROBES

• Broad emission lines • Narrow emission lines• Narrow absorption lines• Variability/reverb. • Broadband/disk/reflection spectra• Polarimetry• Binary Black Holes• Microlensing

(Zoghbi, de Marco, Ponti, Goosmann)

(Iwasawa, Ballantyne, Guainazzi, de la Calle, Svoboda, Miniutti)

(Cappi, Reeves,)

(Dovciak)

(Laor, Walton)

(Cappi)

(Komossa, Liu)

NOBODY!

+ Nikolajuk: TBC

PROBES: MICROLENSING

RX J1131-123116

Chartas et al. 2009Dai et al. 2009

MICROLENSING!

Direct measurement of size of emission region: X-rays from 10 Rg (Optical 70 Rg)

THE PROGRESS

Risaliti et al. 2005NGC1365

Mrk 509 (long-look, 200ks)

MC et al., 2009Dadina et al. ‘05

Obs1

Obs2

Obs3

Variability allows to place limits on location, mass, etc.

(See also Krongold et al. 2007 on NGC4051)

Cappi

PROGRESS: INFLOWS/OUTFLOWS

PROGRESS: HOTSPOTS

Turner et al. 2005Iwasawa et al. 2004

Cappi, Iwasawa, Reeves, De Marco

PROGRESS: THE INNER FLOW

IwasawaNikolajuk

PROGRESS: BROAD LINES

45% of XMM-Newton Seyfert sample with >30,000 counts

Nandra et al. (2007)De La Calle, Guainazzi

PROGRESS: BROAD LINES

Zoghbi

If η implies a*

Fanidakis et al.arXiv:0911.1128

PROGRESS: SPIN MEASUREMENT

Laor: disk continuum fitting

PROGREES: SPIN MEASUREMENT

Miniutti: broad emission lines

SWIFT J1247Fairall-9

Implications for black hole accretion/merger history through cosmic time (also Ballantyne)

PROGRESS: STRONG GRAVITY

IwasawaWalton

Svoboda

THE PROBLEMS

• Broad lines• Predicted to be universal, but not always observed• Degenerate with complex absorption• Lines are much weaker than we might have hoped• Sometimes variable, sometimes now

• Narrow lines• NOT predicted unless extreme anisotropic effects. • Limited statistical significance (Vaughan & Uttley)• “Spallation” of Fe • Non-repeatable observations -> cannot test models• Should be transient (Kepler timescale) – is this too convenient?

• QPOs• Finally one decent AGN example (RE 1034; Middleton)• Ooops it went away (Middleton)• Which QPO to associate with GBHC?• Interpretation in GBHC not clear despite vastly better data

Overall, two major problems:1)Repeatability of observations 2)Prediction and testing of models

PROBLEMS: BROAD LINES

Zoghbi

Absorption highly unlikely to be sole explanation, but details (e.g. spin) very hard to disentangle

K. Nandra: broad lines in AGN

PROBLEMS: BROAD LINES

Disk line upper limits typically 50-100 eV

Criteria: <99% significance for blurred reflection12 total: IC4329A (1) NGC 5506(1), NGC 5548(1) NGC 7469(1)

30% of Sample

Why are broad lines absent? (Almost) unavoidable prediction of accreting

systems…Ionization, Fe abundance, Extreme blurring?

Ignacio de la Calle16 February 2010

6.7

PROBLEMS: S/N RATIO

De la Calle

PROBLEMS: NARROW FEATURES Lines statistical significance? (transient

features, number of trials in time and energy, etc…)

Identifications of edges/lines energies? (Kallman et al. 2005, Kaspi et al. for

PG1211)

Local “contamination”? (PDS456 at risk? McKernan et al. ’04, ‘05)

Publication bias? Only positive detection, low signif., Vaughan & Uttley ‘08)

cz (km/s)

Out

flow

v (

km/s

)

Solutions: Large Samples, Systematic analysis:Cappi, de Marco, de la Calle, Ponti

Strong narrow K line at 6.4 keV. Constant flux over 3 years.

However redshifted but relatively narrow line emission is observed at 5.4 keV and 5.9 keV in 2005 low state.

Obs 1 vs Obs2

PROBLEMS: NARROW LINES

Reeves

PROBLEMS: NARROW LINES

Suzaku All XMM co-add

Mostly S. Vaughan

5.4 keV

If 5.4 keV is real, it is variable (thus not spallation)

Reeves

PROBLEMS: LINE VARIABILITYBhayani & Nandra (2010)

Variability key to break degeneracies: Iwasawa, Zoghbi, Reeves, de Marco, Ponti, Goosmann

BUT… source behaviour not predictable with current models

PROSPECTS: REVERBERATION

Zoghbi Reeves

PROSPECTS: POLARIZATION

Dovciak

X-ray polarimetry: a new window to be opened by GEMS, NHXM, IXO

PROSPECTS: BH SPINASTRO-H: First high resolution, high throughput spectroscopy at 6 keV

IXO XMSNGC 3783 300ks

MCG-6-30-15 100ks

IXO

IXO: ULTRA-HIGH THROUGHPUT

IXO

ASTRO-H

PROSPECTS: TRACING HOTSPOTS

IXO: high throughput

Flux constraint ~20%

400s exposure:1/10 tKeplerian at 6 rg

C. Reynolds

PROSPECTS: TESTING GR?

GR correct

=0.5

0.2=0.0 (GR)

Johanssen & Psaltis (2009)

Testing the no-hair theorem=0

C. Reynolds

PROGNOSIS

• Strong gravity effects in AGN can be probed• For example, lensing shows X-rays arise within ~10 Rg

• Major issues:• Model degeneracies• Unrepeatable observations• Lack of testable model framework

• Major progress• Large samples, systematic analysis• Variability studies, reverberation

• Huge future potential • High resolution spectroscopy• High throughput spectroscopy• Polarimetry

See you in Progue 2020!

Promising Prospects for Proactive Promotion of Proposed Projects

IXO